1. A regression analysis includes the effect of Age, which is categorised into five levels. How many dummy variables should be defined for including it in the analysis?
2. A regression analysis includes Sex as an explanatory variable. How many dummy variables are required to be defined?
3. A regression analysis has:
-five continuous variables;
-sex;
-ethnic group with five levels; and
-education at four levels.
What is the degress of freedom of the regression sum of squares in the ANOVA table?
4. When point A is removed from a regression analysis the correlation coefficient increases. Which one of the following must be correct?
Select one:
a. A corresponds to a large residual value.
b. A is an outlier.
c. A should not be removed from the regression.
d. A is a point of high leverage.
5. When point A is removed from a regression analysis the correlation coefficient decreases. Which one of the following must be correct.
Select one:
a. A corresponds to a low residual value.
b. A is an outlier.
c. A is a point of high leverage.
d. A should not be removed from the regression.
6. In a multiple regression the first full model is fitted with all the explanatory variables. Several of the variables are not significant. Which one of the following is the best way to proceed?
Select one:
a. Remove all the non-significant variables from the model.
b. Remove the variable with the lowest p-value first.
c. Remove the non-significant variable with the largest p-value first,
d. There is no need to remove any variables, as this will reduce the coefficient of variation.
1 answer
1 answer