An educational psychologist studies the effect of frequent testing on retention of class material. In one section of an introductory course, students are given quizzes each week. A second section of the same course receives only two tests during the semester. At the end of the semester, both sections receive the same final exam, and the scores are summarized below. Frequent Quizzes Two Exams n = 20 n = 20 M = 73 M = 68 A. If the first sample variance is s2 = 38 and the second sample has s2 = 42, do the data indicate that testing frequency has a significant effect on performance? Use a two- tailed test at the .05 level of significance. (Note: Because the two sample are the same size, the pooled variance is simply the average of the two sample variances.) tcritical = ____________________________________ sp² = ____________________________________ S(M1-M2) = ____________________________________ tcalculated = _____________________________________________________ Decision = ___________________________________ B. If the first sample variance is s2 = 84 and the second sample has s2 = 96, do the data indicate that testing frequency has a significant effect? Again, use a two-tailed test with α = .05. tcritical = ____________________________________ sp² = ________________________________________ S(M1-M2) = ____________________________________ tcalculated = _____________________________________________________ Decision = ___________________________________
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.
An educational psychologist studies the effect of frequent testing on retention of class material. In one section of an introductory course, students are given quizzes each week. A second section of the same course receives only two tests during the semester. At the end of the semester, both sections receive the same final exam, and the scores are summarized below.
Frequent Quizzes Two Exams
n = 20 n = 20
M = 73 M = 68
A. If the first sample variance is s2 = 38 and the second sample has s2 = 42, do the data
indicate that testing frequency has a significant effect on performance? Use a two-
tailed test at the .05 level of significance. (Note: Because the two sample are the same
size, the pooled variance is simply the average of the two sample variances.)
tcritical = ____________________________________
sp² = ____________________________________
S(M1-M2) = ____________________________________
tcalculated = _____________________________________________________
Decision = ___________________________________
B. If the first sample variance is s2 = 84 and the second sample has s2 = 96, do the data
indicate that testing frequency has a significant effect? Again, use a two-tailed test with
α = .05.
tcritical = ____________________________________
sp² = ________________________________________
S(M1-M2) = ____________________________________
tcalculated = _____________________________________________________
Decision = ___________________________________
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 17 images
