Question

Question 10 Which of the following is an example of a paired test? o A teacher compares the scores of students in her class on a standardized test with the national average score. o A teacher calculates the average of scores of students on a pair of tests and wishes to see if this average is larger than 80%. o A teacher compares the pre-test and post-test scores of students. o A teacher compares the scores of students using a computer-based method of instruction with the scores of other students using a traditional method of instruction. Question 11 Which of the following would be the most likely result when an irrelevant (or insignificant) independent variable is added to a regression model? O A decrease in R2 and an increase in adjusted R2 O An increase in both R2 and adjusted R2 o A decrease in both R2 and adjusted R2 O An increase in R2 and a decrease in adjusted R2 Question 12 Which of the following is(are) correct regarding indicator variables? o (a) Indicator variables are needed to quantify a categorical variable. o (b) A categorical variable with d categories requires d - 1 indicator variables. (c) Indicator variables assume only the intercept is different and the slopes of all other explanatory variables are constant across all categories. o (a) and (b) o (a) and (c) o (b) and (c) o (a), (b), and (c) Question 13 If the spread of residuals increases as the response increases, which of the following is the most common approach to correct this type of pattern? o Consider a non-linear function of one or more explanatory variables. o Add a new explanatory variable. O Transform the response variable. o Increase the sample size.

Answer 1

Solution:

10) A paired sample t test is used to compare before and after observarions of same subject.

Hence, option c is correct, i.e.

c) A teacher compare the pre-test and post-test scores of students.

11) when we add a new independent variable in the model then the R square value is always increases but the value of adjusted R square is increases only when the independent variable is significant.

Hence, option D is correct, i.e.

d) An increase in R suare and a decrease in adjusted R square.

12) An indicator variable is used to quantify categorical variable also if there are d catogories then we need d-1 indicator varibles.

option c is incorrect because the slopes of all other explanatory variable assume different values while the intercept term is constant.

Hence, option a and b is correct.

13) If the spread of a residual increases as the response increases, then the most common approach is to take a transformation of the response variables.

Hence, option c is correct. i.e

Transform the response vriable.