Which statement is true about cross-validation.
A)It can be used for evaluating the model for chance variations in the data and other problems associated with regression.
B)It examines whether the regression model continues to hold on comparable data not used in the estimation.
C)A special form of validation is called double cross-validation where the sample is split into halves.
D)All of the above statements are true.
________ variables may be used as predictors or independent variables by coding them as dummy variables.
D)All of the above
The regression equation for a categorical variable with four categories would be modeled as ________.
A)Ŷi = a + b1 D1 + b2 D2 + b3D3
B)Ŷi = a + b1 D1 + b2 D2 + b3D3 + b4D4
C)Ŷ = b1 D1 + b2 D2 + b3D3
D)Ŷ = b1 D1 + b2 D2 + b3D3 + b4D4
Suppose a researcher wants to explain attitudes towards a respondent's city of residence in terms of duration of residence in the city. The attitude is measured on an 11-point scale and the duration of residence is measured in terms of the number of years the respondent has lived in the city. In a pretest of 12 respondents, the calculated t value for the correlation coefficient based on the data given is 8.414. The critical value of t for a two-tailed test and α = 0.05 is 2.228. r = .9361. What is the null hypothesis for this scenario? What do the results mean in terms of the null hypothesis and the correlation coefficient, r?