Customer database. A large philanthropic organization keeps records on the people who have contributed to their cause. In addition to keeping records of past giving, the organization buys demographic data on neighborhoods from the U.S. Census Bureau. Eighteen of these variables concern the ethnicity of the neighborhood of the donor. Here is a histogram and summary statistics for the percentage of whites in the neighborhoods of 500 donors.

a) Which is a better summary of the percentage of white residents in the neighborhoods, the mean or the median?
Explain.

b) Which is a better summary of the spread, the IQR or the standard deviation? Explain.

c) From a Normal model, about what percentage of neighborhoods should have a percent white residents within one standard deviation of the mean?

d) What percentage of neighborhoods actually have a percent white within one standard deviation of the mean?

e) Explain the problem in using the Normal model for these data.

Transcribed Image Text:

250 200 150 100 50 # of Neighborhoods 0 25 25 % White 50 75 100 Count 500 Mean 83.59 Median 93 StdDev 22.26 IQR 17 Q1 80 Q3 97