14 11 18 9
Look at the following table. What type of correlation coefficient would you use to examine the relationship between ethnicity( defined as different categories) and political affiliation? How about club membership( yes or no) and high school GPA? Explain why you selected the answers you did.
Level of Measurement and Examples Variable X Variable Y Type of correlation Correlation being computed Nominal( voting preference, such as Republican or Democrat) Nominal( gender, such as male or female) Phi coefficient The correlation between voting preference and gender Nominal( social class, such as high, medium, or low) Ordinal( rank in high school graduating class) Rank biserial coefficient The correlation between social class and rank in high school Nominal( family configuration, such as intact or single parent) Interval( grade point average) Point biserial The correlation between family configuration and grade point average Ordinal( height converted to rank) Ordinal( weight converted to rank) Spearman rank correlation coefficient The correlation between height and weight Interval( number of problems solved) Interval( age in years) Pearson product-moment correlation coefficient The correlation between number of problems solved and the age in years
When two variables are correlated( such as strength and running speed), it also means that they are associated with one another. But if they are associated with one another, then why does one not cause the other?
Given the following information, use Table B. 4 in Appendix B of Statistics for People Who( Think They) Hate Statistics to determine whether the correlations are significant and how you would interpret the results.
a. The correlation between speed and strength for 20 women is. 567. Test these results at the. 01 level using a one-tailed test.
b. The correlation between the number correct on a math test and the time it takes to complete the test is. 45. Test whether this correlation is significant for 80 children at the. 05 level of significance. Choose either a one- or a two-tailed test and justify your choice.
c. The correlation between number of friends and grade point average( GPA) for 50 adolescents is. 37. Is this significant at the. 05 level for a two-tailed test?
Use the data in Ch. 15 Data Set 3 to answer the questions below. Do this one manually or use IBM SPSS software.
a. Compute the correlation between income and level of education.