There are 25 children in a class: 15 boys and 10 girls. When report cards are issued, 10 "A" grades are given in mathematics. Seven of the "A" grades go to boys and 3 go to girls. The parents of the girls complain that boys receive significantly more "A" grades than girls do.
a. What are the two variables in this study?
b. State the null hypothesis.
c. What is the df for this study?
d. Create a table of observed and expected frequencies. Use row and column totals to compute expected frequencies. Put the expected frequencies in parentheses.
e. Calculate x2-
f. Interpret the result at the .01 and .05 error levels: Can you reject the null hypothesis? If so, with what level of confidence?
g. Even if the complaint were statistically justified, that would not necessarily imply that there is gender bias in the instruction or grading. What aspect of the design of this study makes it difficult to assign cause to the independent variable, gender?