A teacher gives a reading skills test to a third grade class

A teacher gives a reading skills test to a third grade class od n=25 at the beginning of the school year. To evaluate the changes that occur during the year, students are tested again at the end of the year. Their test scores showed an average improvements of MD=12.7 points with S^2=100.

a. State the null hypothesis
b. Compute the becessary hypothesis test using a two-tailed test with alpha=.05. Show your calculations
c. Make a decision about youir null hypothesis. (Include the critical value you used to bade your decision.)
d. Write an APA format statement summarizing your findings (include a measure of effect size if necessary.)

Solution

A) The null hypothesis is that the mean scores of the students have remained the same over the year.

B)

z-stat = MD / (s / sqrt(n) )

= 12.7/ (10/sqrt(25) )

= 12.7 / 2

= 6.35

C)

Critical Value of a z-test at alpha = 0.05 is 1.96

Since,the calculated value is beyond 1.96, the null hypothesis has to be rejected.

Hence, there has been a change in the scores of the students.

D)

I am unsure about APA statements. However, the effect of size would be a reduction in the standard error in measurements.

Hope this helps.