11.4 - Key Concepts in the Analysis of Cross-Sectional Studies

Question 1

Varying Reliability of Measures

Answer 1

Two measures can only correlate to the extent that each measure is reliable.
Possible to adjust the correlation between 2 variables so that it is based on ‘perfectly reliable’ measures.

Question 2

Third Variable Issue

Answer 2

Can affect the correlation between 2 variables - reduce, inflate the correlation or even reverse its sign
Statistical adjustments to ‘get rid’ of the effect of third variables including the partial correlation coefficient

Question 3

Partial Correlation Coefficient

Answer 3

A coefficient to describe the relationship between X and Y when taking away the effects of control variable Z , which can be used to test conditional independence.

Question 4

Restricted Variation of Scores

Answer 4

Correlational between intelligence and income will be higher in the general population but smaller if a sample of people with university degrees is chosen