(a) The correlation between number of married residents and number of unemployed residents in 2008 for the 50 states and Washington, DC, is 0.922. A scatter diagram of the data drawn in MINITAB is shown on the following page. What type of relation appears to exist between number of marriages and number unemployed?

(b) A lurking variable is in the relation presented in part (a). Use the following correlation matrix to explain how population is a lurking variable.

(c) The correlation between unemployment rate (number unemployed divided by population size) and marriage rate (number married divided by population size) in 2008 for the 50 states and Washington, DC, is 0.050. A scatter diagram between unemployment rate and marriage rate drawn in MINITAB is shown next. What type of relation appears to exist between unemployment rate and marriage rate?

(d) Write a few sentences to explain the danger in using correlation to conclude that a relation exists between two variables without considering lurking variables.

Transcribed Image Text:

Marriages vs Number of Unemployed, 2008 250 200 8 150 100 50 200 400 600 Unemployed 800 1000 1200 1400 Correlations: Unemployed, Population, Marriages Unemployed Population Population Marriages 0.979 0.922 0.947 Cell Contents: Pearson correlation Marriage Rate vs Unemployment Rate, 2008 40 30 E 20 10 7 Unemployment Rate