Exam 12: Analysis of Variance

The variance, or mean square, results from dividing the SS by the degrees of freedom.

If the MS between equals 10, and the MS within equals 10, the total degrees of freedom are equal to

The F ratio can never be significant unless

When an F ratio is significant, the null hypothesis is accepted.

Within variability results from the accumulated differences between each individual score and the total mean.

When the distribution of raw scores within a sample forms a leptokurtic shape, then

For questions below use the data on the following page: A researcher is interested in establishing whether memory is a function of both IQ and time of testing. A random sample of 40 university students was selected and each student was given an IQ test. Half of the students scored above 115 and were assigned to the high IQ category. The students were than all given a series of paragraphs to read, followed by a memory test on the content of what had been read. Half the students took the memory test immediately after reading the material, while the other half waited an hour before testing. The results were as follows (high scores indicating better memory retention): -Find the MS for columns.

Comparing all means from a four-group design would require the calculation of