Mapping Cultural Participation in Chicago - Cultural Policy Center

Appendix IIIModeling and PredictionTo calculate our measure of unexpected participation, we specified and estimated theparameters of a statistical model that related the participation density in artsorganizations for each census tract to several socioeconomic characteristics for thattract.• To account for differences in income among areas we used the natural log of themedian household income in the tract. We also experimented with using medianincome and its square.• To account for educational attainment we used the percentage, and its square, ofresidents over 25 years of age who had a bachelor’s degree. We also controlled forthe percentage of residents that had a master’s level or higher degree.• To account for the age structure of the census tract we used the percentage ofresidents between the ages of 35 and 49 and between the ages of 50 and 65. We alsointeracted these two age variables with the percentage of residents with a bachelor’sdegree.• To account for differences in household structure among tracts we considered theaverage household size, percentage of households headed by a female with children,percentage of households with children, and percentage of households with onemember. Once we accounted for these variables, the percentage of householdsheaded by a woman with children had no explanatory power in the model and so itwas dropped from our analysis.We measured participation in our analysis as the natural log of the participation densityin large organizations. Each of the socioeconomic characteristics was related linearly tothis variable. We estimated our statistical model using the method of least squares. Weconsidered several variations on the model where we included or excluded some of thevariables described above. We also alternatively excluded some census tracts from theanalysis depending on their small size. We weighted the observations by the number ofoccupied households in the census tract. Finally, we adjusted downward the participationdensities in the downtown Loop community area to account for the relatively largenumber of business addresses from this part of the city in our database. The purpose ofestimating these variations in our statistical model was to see whether our findings onethnic composition of a community were sensitive to our specification and assumptionsabout the data.The unit of analysis was the census tract. There are 865 such tracts in Chicago. Becausewe excluded tracts with small numbers of people, we used only 810.55