KNR 445
Statistical Applications in Science & Technology

Dependent (paired) t-test

The purpose of this assignment is to introduce the concept of the dependent t-test, used to compare the mean difference between two correlated sets of data. The data to be used includes the data set indep_t3

Homework

1. What benefit is gained by giving both treatments to a single group rather than giving the treatments to two different groups of subjects (ie what is the benefit of a repeated measures design compared to a between subjects design)?

2. Last week, you created an SPSS file with the data in file indep_t3
    a. Conduct an independent t-test between the two groups (CHO_sup and Regular diet).
    b. Create a new data file using the same data but arranged as if each case of the CHO sup data and the Regular diet data were both collected from the same subject.
    c. Conduct a dependent (paired) t-test between the two data sets.
        i. Is the difference statistically significant at alpha = 0.01?
        ii. Is the difference statistically significant at alpha = 0.05?
        iii. Is the difference statistically significant at alpha = 0.10?
    d. Write a paragraph to justify your selection of an alpha level.
    e. Write a paragraph presenting the results of the dependent t-test, using the format presented in your lecture overhead notes.
    f. Why was the difference statistically significant with the paired t-test but not with the independent t-test?
SPSS Output