A random sample of 115 students enrolled in statistics units in recent semesters at Macquarie University has been selected to study use of practice quizzes and academic performance. Some of the variables recorded for each student are listed below.

VariableDescription

subid

Subject ID

intDom

domestic or international

numQuizzes

the number of practice quizzes attempted

unitMark

the final unit mark

A simple linear regression is run to answer the research question, ’What is the relation between the final unit mark and the number of practice quizzes attempted?’ The results of the analysis are reported below:

        Estimate Std. Error t value Pr(>|t|)

(Intercept) 42.3520 2.5574 16.5604 0 numQuizzes 0.5947 0.0689 8.6312 0

Address the following questions, assuming as necessary that all test assumptions are verified.

What is the null hypothesis? Choose one among the following options:

a. There is a significant relation, linear or non-linear, between the two variables

b. The slope of the regression line is either positive or negative

c. The relation between the two variables is linear

d. The slope of the regression line is significantly different from zero

e. There is no relation whatsoever, linear or non-linear, between the two variables

f. The slope of the regression line is zero