What is the null hypothesis of a test for correlation?

Which is NOT an example of statistical bias?       Response Bias   Observer Effect   Recall Bias   Placebo Effect

Tips It’s commonly believed that people use tips toreward good service. A researcher for the hospitalityindustry examined tips and ratings of service qualityfrom 2645 dining parties at 21 different restaurants. The correlation between ratings of service and tip percent-ages was 0.11. (M. Lynn and M. McCall, “Gratitude and Gratuity.” Journal of Socio-Economics 29: 203–214)a) Describe the relationship between Quality of Serviceand Tip Size.b) Find and interpret the value of R2 in this context.

A study wants to see if a program aimed at increasing reading accuracy works for elementary school students. They have a group of 20 participants. All 20 get measured at the beginning of the study, and measured again at the completion of the reading program. This is an example of a: Within subjects study Between subjects study A correlation study A mixed design study The main difference between an ANOVA and a t-test is: Group of answer choices An ANOVA can look at more than 2, and t-test looks at only 2 means at a time An ANOVA looks at only 2 means at a time, and t-test can look at more than 2 A t-test can have nominal dependent variables An ANOVA can have a nominal dependent variable