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A researcher wants to know whether an educational video about genetics is effective. This researcher created a quiz assessing knowledge about genetics. She recruited 6 undergraduates and gave them the quiz as a pre-test. Then they watched the educational video, and took the test a second time.
Student Pre-test Post-test
Anne 2 7
Bob 4 5
Cathy 5 7
Dave 7 8
Emma 2 9
Fred 4 6
Compute the r-square estimate of the effect size for this test
Given that,
A researcher wants to know whether an educational video about genetics is effective. This researcher created a quiz assessing knowledge about genetics. She recruited 6 undergraduates and gave them the quiz as a pre-test. Then they watched the educational video, and took the test a second time.
Sample size
The difference between two paired samples is calculated using formula as follows:
|
pretest |
posttest |
Difference (d) |
| 2 | 7 | -5 |
| 4 | 5 | -1 |
| 5 | 7 | -2 |
| 7 | 8 | -1 |
| 2 | 9 | -7 |
| 4 | 6 | -2 |
Mean and standard deviation of difference is calculated using EXCEL functions as given below:
Mean: “=AVERAGE (select array of data values)”
Standard deviation: “=STDEV (select array of data values)”
The mean of the difference is
Standard deviation of difference
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