A professor in the psychology department would like to determine whether there has been a significant change in grading practices over the years. It is known that the overall grade distribution for the department in 1985 had 14% As, 26% Bs, 31% Cs, 19% Ds, and 10% Fs. A sample of n = 200 psychology students from last semester produced the following grade distribution: A |B |C |D |F 32|61|64|31|12 Do the data indicate a significant change in the grade distribution? Test at the .05 level of significance.
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 professor in the psychology department would like
to determine whether there has been a significant
change in grading practices over the years. It is known
that the overall grade distribution for the department in
1985 had 14% As, 26% Bs, 31% Cs, 19% Ds, and 10%
Fs. A sample of n = 200 psychology students from last
semester produced the following grade distribution:
A |B |C |D |F
32|61|64|31|12
Do the data indicate a significant change in the grade
distribution? Test at the .05 level of significance.
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