AP Statistics Section 14.2 B

We can use the chi-square test of association/independence to test the null hypothesis   “ There is ____ association between the two categorical variables.”   when you have a two-way table from a single SRS, with each individual classified according to both of two categorical variables.  

Example: North Carolina State University studied student performance in a course required for its chemical engineering major. One question of interest is the relationship between time spent in extracurricular activities and whether a student earned a C or better in the course. Here are the data for 119 students who answered a question about extracurricular activities.

Grade < 2 2 to 12 >12 C or better 11 68 3 D or F 9 23 5

a) Find the proportion of students (C or better) in each of the three extracurricular activity groups. What do these proportions show?

b) Carry out an appropriate significance test b) Carry out an appropriate significance test. Hypothesis: The population of interest is _____________________________________________ H0: __________________________________________ Ha: __________________________________________

Conditions:

Calculations:

Conclusions:

c) Which term(s) contribute the most to c) Which term(s) contribute the most to ? What does this show you about the relationship between the time spent in extracurricular activities and academic performance in this particular course?

d) Does the study convince you that there is a relationship between the amount of time spent in extracurricular activities and academic performance in this course?