Can You Party Your Way to Better Health? A Propensity Score Analysis of Block Parties and Health

While other indicators of social capital have been linked to health, the role of block parties on health in Black neighborhoods and on Black residents is understudied. Block parties exhibit several features of bonding social capital and are present in nearly 90% of Philadelphia’s predominantly Black neighborhoods. This analysis investigated: (1) whether or not block parties are an indicator of bonding social capital in Black neighborhoods; (2) the degree to which block parties might be related to self-rated health in the ways that other bonding social indicators are related to health; and (3) whether or not block parties are associated with average self-rated health for Black residents particularly. Using census tract-level indicators of bonding social capital and records of block parties from 2003 to 2008 for 381 Philadelphia neighborhoods (defined by census tracts), an ecological-level propensity score was generated to assess the propensity for a block party, adjusting for population demographics, neighborhood characteristics, neighborhood


INTRODUCTION
The concept of social capital grows from the observation that social relationships can create a form of capital that can have positive effects on multiple outcomes, including health (Hanifan, 1916;I. Kawachi, 1999;Putnam, 1993Putnam, , 1995)).Social capital may be considered the ecological analog to individually-based social support, and is considered a social determinant of health and health behaviors.Social capital relates to resources embedded within groups, i.e. it is a contextual construct, and is distinguished from social support because social support relates to interpersonal relationships at the individual level.Studies of social capital and self-rated health overwhelmingly support that high social capital is related to better self-rated health (Ichiro Kawachi, Subramanian, & Kim, 2007).Public health researchers have offered that social capital may be positively associated with health through: diffusion of information about health-promoting behaviors; maintenance of healthy behavioral norms or deterrence of risky behaviors through informal social control; promotion of access to services; affective support or other psychosocial pathways that act directly or indirectly; and empowerment to engage political policies that impact community health (Berkman & Kawachi, I 2000;Kawachi & Berkman, 2001;Ichiro Kawachi et al., 2007).
Examining differences in social capital and health within racial/ethnic groups is important because there is often more variation in health outcomes within racial/ethnic groups than between them, which is true for the Black/African-American population in the US (Arthur & Katkin, 2006;Read & Emerson, 2005;Williams, 1997;Williams & Jackson, 2000).Further, there is a need to explore what might be culturally-relevant indicators of social capital that are prevalent in Black neighborhoods, for example block parties (Dean & Gilbert, 2010;Gilbert & Dean, 2013).

Block Parties as a Space for Cultivating Social Capital
By nature, cultivating social capital must occur in a community-based context, which can occur within one's residential neighborhood.As Oliver & Myers define them, "block parties are generally understood… to be consensual events that convey a sense of sociability and community to residents of a particular area" (Oliver & Meyer, 1999) who feel a sense of collective belonging and solidarity.By that definition, block parties may be relevant to forms of bonding social capital because they are a manifestation of solidarity among residents within a neighborhood.Bonding social capital refers to resources that are available to members of a group who are similar to each other with respect to social position and identity (Kim, Subramanian, & Kawachi, 2006) and who are of the same community (Harpham, 2008), making it particularly relevant for research on neighborhoods.It may exist within the context of racial/ethnic groupings or geographic locations where people who are demographically similar would interact (Poortinga, 2012), especially in cities that are highly segregated by race.Bonding social capital, in the forms of social trust, reciprocity, and civic participation, has been linked to better subjective mental health outcomes (Fone et al., 2007;McKenzie, Whitley, & Weich, 2002), lower suicide rates (Helliwell, 2004) and violent crime (Kennedy, Kawachi, Prothrow-Stith, Lochner, & Gupta, 1998), and may be a buffer to the adverse effects of neighborhood deprivation (Cattell, 2001;Fone et al., 2007;McKenzie et al., 2002).Block parties might also reflect collective efficacy, or the collective willingness of residents to intervene on behalf of the common good based on mutual trust and solidarity among residents (Kim, Subramanian, & Kawachi, 2007;Sampson, Raudenbush, & Earls, 1997) because neighborhood residents must sign a petition agreeing to allow the block party.Block parties might represent social cohesion, or how interconnected the group is, social participation, or participation in local organizations, and volunteerism, how involved the group is in service activities, all of which are social capital indicators that have been associated with health.That is to say, block parties may be a context in which the mechanisms between social capital and health are at work.For instance, block parties may be a space where neighbors exchange information about how to keep healthy, or knowing that neighbors might disapprove of risky behaviors, might discourage unhealthy actions through informal social control.
Block parties may be especially important for certain neighborhoods over others.By year 2008, nearly 90% of the 162 predominantly Black neighborhoods (as defined by when the raw number of Blacks per census count was higher than any other racial/ethnic category in that census tract) in Philadelphia had at least one block party per year, yet few researchers have looked at how block parties may be related to social capital for Black neighborhoods.Block parties tend to be in neighborhoods with long-term residents that have an established block captain who gathers the requisite 75% of signatures on the petition to get a block party permit (Hang, 2006).Block parties are informal gatherings that may occur once or up to a few times per year, require few resources to host, and which require little preparation beyond the initial petition and advertisement by posting flyers or word-of-mouth.They create a space for relationship-building and sharing about resources available in the neighborhood.With increased commute times between work and home that keep residents away from their neighborhoods, block parties are a space for neighbors to connect and feel mutually supported.They may be a symbol of the residents' ability to come together and lay a platform to address more complex social issues (Hang, 2006).
To date, no published research studies have explored block parties in the context of social capital mechanisms in Black neighborhoods, though the potential benefits of block parties have been noted (Oliver & Meyer, 1999).Furthermore, examining block parties in isolation of other neighborhood structures removes it from the social and environmental contexts that frame how social capital is fostered.Block parties need to be explored in the context of the characteristics of the neighborhoods in which they exist.Neighborhood resources, residential characteristics (e.g., housing density, residential segregation), crime, and neighborhood demographics, may be potential confounders between block parties as a form of social capital, and self-rated health for Black neighborhoods.A neighborhood with available economic developments such as banks, check-cashing establishments, high homeownership or symbols of social investment such as murals and community development corporations might indicate a neighborhood that has been invested in by neighbors and by city government.Longer commute times to work may be an indicator of less time to spend in one's neighborhood or fewer economic resources for employment in or near one's residential neighborhood.The physical boundaries and spatial layouts of the neighborhood may affect whether or not a block party can physically exist, and social characteristics may affect the likelihood that a block party will happen.For example, living in an area where houses are close together and have a high housing density would provide a physical space to hold a block party.Thus, accounting for number of households, housing units, families, overcrowding and residential blocks per square mile could be important.Areas that are unsafe due to high crime rate may have lower social capital (Kennedy et al., 1998;Takagi, Ikeda, & Kawachi, 2012), may cause residents to be fearful of being outdoors, which would erode both social capital and decrease the likelihood of block parties, or conversely be more likely to have block parties if residents come together in targeted efforts to lower crime rates.Black segregated neighborhoods tend to be low-resource, be less safe, and suffer from elements of neighborhood disadvantage (Massey & Denton, 1993;Quillian, 2012) which would be related to health and to whether or not an area is an appropriate setting for a block party.The relationships between block parties and these factors is yet unknown, but should be considered in analysis.Exploring a large number of neighborhood characteristics may require special statistical methods designed for dealing with a high number of confounders, like propensity score analysis.This exploratory analysis uses OLS regression and propensity score matching to assess how a block party, as a potential indicator of social capital, might be related to the average health of Black residents in Philadelphia, Pennsylvania neighborhoods.

METHODS
The first part of the analysis was designed to answer the question of whether or not block parties are an indicator of bonding social capital for Black neighborhoods.It uses OLS regression with social capital indicators as independent variables and block parties as an outcome.The relationship between social capital indicators and self-rated health are explored in parallel, to assess the degree to which conventional social capital indicators are related to health and to see if it mimics the relationship between other bonding social capital indicators and health.The second part of the analysis was designed to explore the association between block parties as an independent variable and self-rated health of Black residents only.

Data Sources and Study Population
All data were de-identified secondary data, thus this analysis was not considered to be human subjects research and met the criteria of being IRB-exempt.For the outcome variable, self-rated health, and the social capital variables, data were combined from the 2004, 2006and 2008 Southeastern Pennsylvania Household Health  Individual-level data were aggregated to census tract levels to obtain neighborhood averages of self-rated health and social capital.Census tracts were proxies for neighborhoods.
Information on other neighborhood resources and characteristics was obtained from the US Census 2000 and the Cartographic Modeling Lab at the University of Pennsylvania, which stores primary data collected by city agencies, publicly accessible data sets.Crime rates were collected from the Philadelphia Crime Lab (http://cml.upenn.edu/crimebase/)based on records from the Philadelphia Police Department.

Key Variables
Block Parties-Block party date and locations from 2003 to 2008 were obtained from the Philadelphia Streets Department's public record, with permission.In order to register a block party, Philadelphia community members must nominate a block captain in their neighborhood to submit an application with at least 75% of a block's signatures to the Department of Streets.The application requests permission for a block party on a specified date, and is usually submitted in the first six months of the year, since the majority of block parties occur between May and August.Because the number of block parties is constrained by the number of blocks in a census tract, a geographic variable was created by dividing the number of block parties in 2008 (the year in which the most tracts had registered a block party) by the number of blocks per square mile within a census tract.
Self-Rated Health-The PHMC data provided the self-rated health variable, which had a 4-point Likert-type response scale for the question "On a typical day, how would you rate your health?"Individual respondents could indicate their health to be "poor", "fair", "good", or "excellent" with higher numbers representing better health outcomes.The self-rated health variable was aggregated to the census tract level, leaving one average self-rated health value assigned to each Philadelphia census tract using the 2000 US Census Tract designations.
Social Capital-The PHMC data are collected at the individual level, but being that social capital is inherently a contextual measure, was aggregated to the census-tract level so that each census tract was assigned one average value per census tract for each dimension of social capital measured.
An oblique (promax) rotated principal components factor analysis suggested a threemeasure composite score to represent social cohesion (alpha=0.71),covering feelings of belongingness, interpersonal trust, and neighborliness: "Please tell me if you strongly agree, agree, disagree, or strongly disagree…: I feel that I belong and am a part of my neighborhood" [belongingness]; "Most people in my neighborhood can be trusted" [interpersonal trust]; and "Please rate how likely people in your neighborhood are willing to help their neighbors with routine activities such as picking up their trash cans, or helping to shovel snow.Would you say that most people in your neighborhood are always, often, sometimes, rarely, or never willing to help their neighbors?"[neighborliness].Higher numbers represented higher social cohesion.
Collective efficacy was represented by the yes-no item "Have people in your neighborhood ever worked together to improve the neighborhood?"In later waves of the data, the question added the prompt "For example, through a neighborhood watch, creating a community garden, building a community playground, or participating in a block party."Social participation was measured by the item "How many local groups or organizations in your neighborhood do you currently participate in such as social, political, religious, schoolrelated, or athletic organizations?" and was recoded to be dichotomous to represent either any participation or none at all.
Volunteerism addressed the frequency of social participation with the item: "How many times in the past 12 months have you volunteered your time to do any unpaid work to help people besides your family and friends or people you work with?"This item was recoded as dichotomous to reflect having volunteered "never" or "one or more times" in the past 12 months.
Neighborhood Characteristics-US Census 2000 census tract data on the number of families, housing units, percent owner or renter occupied, and percent overcrowded were included because the opportunity for block parties may be affected by the housing layout of a neighborhood.The number of census blocks per square mile was calculated by counting the number of census blocks whose center point (centroids) fell within a square mile area.
Neighborhood Resources-Neighborhood resources were selected based on hypothesized or demonstrated relationships with health, social capital, and/or the likelihood of block parties.These include addresses of: murals, check-cashing locations, community development corporations, billboards, banks, and recreation centers.Characteristics were chosen using the Delphi method of consultation with experts in social capital and city planning, and by what data were available for analysis.
Violent Crime-The number of aggravated assaults each year from 2000 through 2006 was included as a metric of violent crime.Aggravated assaults may be a more representative measure of safety than the homicide rate since homicides are calculated only for fatal events, and assaults are calculated by for any violent event.
Segregation-A census-tract level segregation measure based on racial composition was used to account for social exclusion of Black neighborhoods.Recognizing that, in a densely populated area, residents may access resources in blocks adjoining their own, the measure represents a ratio of the exposure of one household within a census tract compared to the potential for interaction across surrounding tracts (Wong, 2002).Philadelphia's tracts are predominantly Black or White, so a 2-group measure was sufficient.This measure has been used in at least three other peer-reviewed published studies (S.Grady, 2006; S. C. Grady & McLafferty, 2007;White et al., 2011).While the segregation measure was intended to capture the degree of interaction that Black neighbors might have with White neighbors, percent race was separately assessed and was intended to capture the raw numbers of Blacks and Whites in a tract.
Population Demographics-The 2000 US Census provided raw counts for race, age, high school graduation rates, poverty, and commute time for each census tract.Predominantly Black neighborhoods were designated as when the raw number of Blacks per census count was higher than any other racial/ethnic category in that census tract.

STATISTICAL APPROACH
Preliminary Analysis: STATA SE10.0 statistical package (StataCorp, 2007) was used to calculate means and standard deviations of key variables.Two-sample t-tests determined if the differences between neighborhoods (tracts) with or without block parties were significant at p<0.05.
To ensure that social capital variables were related both to block parties and to self-rated health, separate OLS regressions were performed with block parties as the outcome and selfrated health as the outcome.For each of the four social capital indicators, social cohesion, collective efficacy, social participation, and volunteerism, a separate linear regression estimated the relationship between each indicator and block parties, and was repeated for self-rated health.Regressions were performed first across all neighborhoods, and then in predominantly Black Philadelphia neighborhoods, all controlling for the percentage of the population below 200% of the federal poverty line per US 2000 Census data.To assess the degree to which the relationship between social capital indicators and block parties may differ for Black or White neighborhoods, an interaction term was included in the final models, representing the interaction between each respective social capital and neighborhood composition, either predominantly Black or predominantly White.After creating regression models and plotting the interactions, simple linear regression generated coefficient estimates, 95% confidence intervals, and p-values for self-rated health and block parties as outcomes, for the percentage of the population below 200% of the federal poverty line per US 2000 Census data.
Propensity Score Matching: Propensity score matching was used to explore the relationship between block parties and self-rated health of Black residents when accounting for other neighborhood characteristics.Because the OLS regression suggested that block parties may only be meaningful to the health of Black residents, the outcome for the propensity-score analysis was aggregated self-rated health scores only for Black respondents.Propensity score matching is a multivariable scoring method that collapses predictors of an exposure or "treatment" into a single value that represents the probability of being exposed, or being "treated," given a set of neighborhood characteristics.It is ideal for isolating the effects of the exposure, block parties, above and beyond other neighborhood-level characteristics (Oakes & Johnson, 2006;Rosenbaum & Rubin, 1983)because it allows for estimation of the effect of having a block party on self-rated health in a non-exposed neighborhood, if that same neighborhood would have had a block party.Propensity score analysis has been increasingly used in cohort and case-control studies (Rassen et al., 2012)[ (Mansson, Joffe, Sun, & Hennessy, 2007) and has been applied to observational data as a means of reducing confounding (Li, Shen, Wu, & Li, 2011;Lin & Chen, 2014).
Propensity score analysis works by minimizing differences between a "treated" group (one that has had a block party) to an untreated group (one that has never had a block party) through matching on common characteristics, a technique used to reduce bias introduced by a large number of covariates in regression.The "treatment" of block parties could not be randomly assigned to neighborhoods, so the propensity score matched neighborhoods that had block parties to similar neighborhoods that did not have block parties, and calculated the difference in self-rated health between the two groups.If a neighborhood with a block party has the same propensity score as a neighborhood without a block party, the two neighborhoods would be expected to have a similar composition of neighborhood characteristics, or covariates, to the extent that the neighborhoods could be considered exchangeable.With the covariate distributions balanced, the assumption is that the only difference between matched scores is the treatment status, or whether or not the neighborhood had a block party.This difference represents the counterfactual hypothetical, or the effect on health that introducing a block party could have on a neighborhood that never had a block party.STATA's pscore (Becker & Ichino, 2002) and psmatch2 Mahalanobis functions (Leuven & Sianesi, 2003) were used to estimate propensity scores using a logit model for the dichotomous outcome for whether or not the neighborhood had registered a block party.The propensity score was stratified into quintiles within which units were matched with replacement, which allowed the use of more of the tracts.The average effect of the treatment on treated using stratification (ATT-s) was calculated within each of the propensity score's strata (within which covariates are balanced and unmatched observations are dropped) and averaged.Stratification helps to achieve 95% of the bias reduction when there are more than 5 strata (Caliendo & Kopeinig, 2008;Cochran & Chambers, 1965;D'Agostino, 1998;Rosenbaum & Rubin, 1983).
For the purposes of comparison, two propensity score estimates were generated: one using a sample of unmatched neighborhoods, and the other using the sample of matched neighborhoods that would benefit from bias reduction.

RESULTS
Of the 381 neighborhoods (defined by census tracts) in Philadelphia, 293 of them had at least one block party between the years of 2003 to 2008.Neighborhoods with block parties were significantly more populated, had higher percentages of females, were more likely to be impoverished, have a higher number of households, families, and housing units, with a higher percentage of Blacks, were more likely to be racially residentially segregated, with more murals, community development corporations, recreation centers, and higher rates of violent crime (Table 1).Neighborhoods with block parties had a significantly lower average rating of self-rated health (score=2.86out of 4) compared with neighborhoods with no block party (mean score of 2.97).
Table 2 compares relationships between social capital indicators and block parties with social capital indicators and self-rated health, with subanalysis on predominantly Black neighborhoods.Social capital indicators were not related to block parties across all neighborhoods; however, predominantly Black neighborhoods had significant and positive associations with block party exposure for social cohesion, collective efficacy, and volunteerism, but not social participation.The interactions between social capital and Black race for block parties were negative and significant for social cohesion and collective efficacy.
Social cohesion, social participation and volunteerism were positively associated with selfrated health across all neighborhoods, but only social participation remained significantly positive when looking within Black neighborhoods.The interaction term estimated that each 1-point increase in social participation was associated with a 0.74 decrease in average health rating in a Black neighborhood.Visual inspection of plots of the interaction model showed that at the lowest levels of social participation, Black neighborhoods report better health than White neighborhoods; however, in all but the areas with lowest social participation, Black neighborhoods have poorer health relative to White neighborhoods.
Standardized differences of each of the neighborhood characteristics before and after matching are reported in Table 3 and provide validation that the covariates in the propensity score are balanced.Prior to propensity score matching, the standardized differences for characteristics between neighborhoods with and without block parties was larger than after matching, resulting in bias reduction.The only exceptions were the percent male and percent high school graduates, which became less balanced and exceeded the 10% threshold after matching.These covariates were later dropped in the propensity score analysis due to an inability to balance the propensity score.The bias reduction achieved by propensity score matching for the remaining variables suggest that propensity score-matched regression model is superior to an unmatched model estimation.Still, despite the bias reduction achieved, some of the standardized differences remained above 10%, indicating that some of the covariates were distributed significantly differently after matching.
After satisfying the covariate balance, the effect of block parties was estimated using the propensity score.The log odds and standard for ATT-s estimates (Figure 2) for the unmatched (0.93, 95% CI:[0.82-1.06])and matched samples (1.10, 95% CI:[0.65-1.87])both have confidence intervals that overlap 1, suggesting that the propensity for exposure to block parties has no effect on self-rated health among Black residents.

DISCUSSION
This analysis attempted to answer the questions of: (1) whether or not block parties are an indicator of bonding social capital in Black neighborhoods, based on OLS regression results; (2) the degree to which block parties might be related to self-rated health in the ways that other bonding social indicators are related to health, based on OLS regression results; and (3) whether or not block parties are associated with average self-rated health for Black residents particularly, using propensity score analysis.Results suggest that while block parties may be an indicator of social capital in Black neighborhoods particularly, block parties are not associated with better or worse self-rated average health of Black residents.
OLS regression results suggest that block parties may be an indicator of social cohesion, collective efficacy, and volunteerism, but not social participation forms of bonding social capital in Black neighborhoods, specifically: associations that do not hold across neighborhoods of other predominant racial/ethnic groups.When examining why this association might be different between Black and White neighborhoods, the negative interaction of social capital and predominant neighborhood race further suggested divergence of Black and White neighborhoods on the value of block parties as a form of social capital.If Black and White neighborhoods diverge on whether or not block parties reflect social capital, this may suggest that indicators by which social capital is measured may need to be culturally tailored.It also calls into question whether or not existing indicators are resonant across cultural groups, and suggests that putting efforts into understanding why different indicators behave differently by cultural groups.For example, higher voter registration rates have been linked to low social capital in Black, low-SEP neighborhoods, but linked to higher social capital in White neighborhoods (Hero, 2004).Using voting as an indicator of social capital in Black neighborhoods may not be a relevant measure, especially for a population that has been marginalized from voting through institutionalized practices to deter civic participation.Such measures of social capital may not be as resonant in Black neighborhoods compared to other racial/ethnic groups and the results of this study suggest that block parties may be culturally resonant indicators of social capital for Black neighborhoods.Beyond being culturally resonant, this analysis suggests that block parties reflect specific dimensions of social capital.In this case, the lack of significant association between block parties and social participation along with the presence of a positive association between volunteerism and block parties may reflect that block parties represent a certain depth of participation, not just whether or not neighborhoods were active.
While block parties may be an indicator of social capital for Black neighborhoods, block parties were not associated with good average self-rated health for Black residents as would be expected since block parties behaved similarly to social capital indictors in the OLS regression.The OLS regression demonstrated that across all neighborhoods higher social cohesion, social participation and volunteerism were related to better self-rated health in this sample, consistent with findings from other research studies (Kim et al., 2007).This preliminarily suggested that if block parties can also be an indicator of social capital, block parties might also be related to health.But when the relationship between block parties and average health ratings of Black residents was directly assessed in the propensity score analysis, block parties were not associated with health, similar to other social capital indicators.These findings may align with several other studies which suggest that the strength of the relationship between social capital indicators is less for Blacks than Whites (I.Kawachi, 1999;Kim et al., 2006;Kim et al., 2007), which reinforces why race, as a social construct, should receive special attention in social capital studies.Social capital may have different returns on health for Black or White neighborhoods.In fact, the positive relationship between social capital and self-rated health largely disappeared when looking within Black neighborhoods only, suggesting that White neighborhoods drive the overall positive associations observed between social capital and health.The interaction term further suggested that social capital may have a different association with health in Black neighborhoods compared with White neighborhoods: in neighborhoods of low social capital, Blacks had better health than Whites, but in neighborhoods of high social capital, Whites had better health than Blacks.One possible explanation for why block parties were not related with self-rated health in propensity score analysis is that Black residents, who are most likely to live in Black neighborhoods given the high degree of residential segregation, may be more likely to face adverse exposures.Deleterious elements in Black neighborhoods with block parties may overshadow any potential positive relationship between block parties and health, similar to what has been found in other studies of social capital and health in Black populations (Cutrona, Russell, Hessling, Brown, & Murry, 2000;Ross, 2000;Schootman et al., 2007).Neighborhoods with block parties had higher rates of violent crime, were more densely populated, overcrowded, had more venues for investing in ways that do not build wealth such as check-cashing vendors and rental property occupancy, and were more likely to be in poverty, all of which are social factors that may overshadow any positive associations between block parties and self-rated health.Conversely, neighborhoods with the most deleterious elements may organize more block parties as a curative action.Even after using the propensity score to account for nearly 30 neighborhood characteristics, including deleterious neighborhood elements, results still suggest that the propensity for block parties had essentially no effect on average self-rated health for Black residents.Residents in neighborhoods that do not have block parties would not be expected to be worse off in terms of health than those that have block parties, even when accounting for their deleterious effects.
A final possible explanation for the null association between block parties and health is that block parties may represent forms of social capital that do not confer health benefit to Black residents.Evidence to support that explanation appear in the OLS regression results for social participation, which was not associated with block parties but was associated with self-rated health in Black neighborhoods.The forms of social capital that are associated with block parties may not be utilized for health promotion, or it may be that neighborhoods with healthier people have less need for the types of social capital that block parties engender.Neighborhoods that do not have block parties may be missing out on the types of social capital that block parties engender, or those neighborhoods may be engaging other forms of social capital.
Simply because block parties are no better or worse for Black self-rated health does not invalidate their potential for health promotion.On the contrary, it is possible that block parties and the forms of social capital they engender have not been fully leveraged for promotion of healthy behaviors.Block parties may operate on health behaviors via the mechanisms common to other indicators of social capital: through diffusion of health information, social control that deters unhealthy behaviors, promotion of health-related services, affective support, and political empowerment (Berkman & Kawachi, 2000;Gilbert & Dean, 2013;I. Kawachi & Berkman, 2001;Ichiro Kawachi et al., 2007).As block parties are most relevant to Black neighborhoods, interventionists may consider them an entry point to encourage health behaviors that can reduce health disparities in diseases for which Blacks are at higher risk, and for which disparities have persisted despite existing interventions.For example, there is some evidence that social capital is related to more cancer screening behaviors (Leader & Michael, 2013), which applies in Black neighborhoods (L.Dean et al., 2014;L. T. Dean et al., 2014).This may be because block parties can provide a space for residents to share and encourage about these behaviors, or for connecting residents to services.Further exploration of the role of block parties on health behaviors is warranted.

Limitations
The response rate to the PHMC questions was low; however, PHMC's response rates fall within the range of response rates of other well-used and respected community-based surveys that use random-digit dialing, like the California Health Interview Survey (California Health Interview, 2009), and the nationally renowned Behavioral Risk Factor Surveillance System (Centers for Disease & Prevention, 2009).
A common critique of social capital indicators is that endogeneity arises when social capital indicators are actually precursors or consequences of social capital (Kim et al., 2007).As an example, in a later wave of the PHMC questionnaire, the collective efficacy item asked if the respondent had participated in an event "like a block party."Using an item like this for this analysis is akin to asking if someone had ever participated in a block party, and then attempting to show how the answer to that question predicts actual block party participation rates.The question's response is in fact its own predictor.However, the distribution of the response to this question matched that of the earlier waves when the block party portion was not asked, so was retained in the combined social capital averages.
Census data from year 2000 and crime data from 2000 to 2006 did not completely overlap with block party data collected from 2003 to 2008.The gap helped to account for any lagged effects that neighborhood characteristics or crime may have had on future block parties.
As an exploratory study, and the first of its kind, there was no previous research to inform the choice of neighborhood-level variables, and so variables that were statistically reliable and readily available were used.The data from the CML and the Streets Department, though readily available, may not have been complete, in which case neighborhood characteristics may be more or less similar than reported.

CONCLUSION
Plainly speaking, if a Black neighborhood that had never had a block party decided to have one, throwing a block party would be no better or no worse for health.Though block parties may be considered an indicator of social capital for Black neighborhoods, they were not associated with average self-rated health of Black residents; however many of the conventional social capital indicators were also not associated with health in predominantly Black neighborhoods.The null effect of propensity for block parties on health leaves room for further exploration, but the potential use of block parties as an indicator for social capital in Black neighborhoods opens a new opportunity for understanding which social resources are available to be leveraged for health promotion.The results suggest that block parties may be related to social cohesion, collective efficacy, and volunteerism for Black neighborhood residents.Results affirm that accounting for race is important in understanding neighborhood social capital.Further analysis might use a different selection of neighborhood characteristics to comprise the propensity score, such as structural characteristics like the number of schools or parks.Further analysis might also consider using a different outcome variable than self-rated health, like health behaviors.Whatever the case, block parties are yet an understudied resource in Black neighborhoods and they should be given more attention in future research and in consideration of health interventions for Black populations.

■
Block parties may be a resonant social capital indicator in Black neighborhoods ■ Block parties may not be worse or better for self-rated health for Black residents ■ Propensity scores can address unmeasured confounding in neighborhood research Treatment Effect of Block Parties on Good Self-Rated Health of Black Residents in Philadelphia Figure 1.

Table 1
Characteristics of Philadelphia Neighborhoods (Census Tract Averages) based on Presence or Absence of Block Parties * Soc Sci Med.Author manuscript; available in PMC 2016 August 01.

Table 2
Associations between Social Capital Indicators and Block Parties compared with Associations between Social Capital Indicators and Self-Rated Health Soc Sci Med.Author manuscript; available in PMC 2016 August 01.