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
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
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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