Exam 12: Analysis of Variance

If the MS between equals 10, and the MS within equals 5, then the F ratio equals

With a two-group experimental design, the independent variable has been manipulated at

When analyzing experimental research via the F ratio, the number of sample groups, and the number of subjects in each sample group, are most clearly shown in the value of the

Once an F ratio has been found not to be significant, we must immediately

The smallest possible value for the SS, sum of squares, is

A within MS of zero, indicates that all the sample scores are identical.

The sum of squares components relate such that SS within is equal to

Analysis of experimental data by the F ratio means that the independent variable could have been manipulated

The less overlap there is among the various sample-group distributions

When the between sum of squares is relatively large, then the shape of the sampling distribution is necessarily

The concept of "within variability" is based on

The concept of "total variability" is based on

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 F ratio for the interaction, and if significant, state the alpha level.

Tukey's HSD is used in order to

The SS, sum of squares, is equal to

When the SS, sum of squares, is large, so too is the

The F ratio, like the t ratio, can be used to predict the direction of the mean difference.

Questions below are based on the following: (This is similar to an item in the text at the back of chapter 12 but WITH A DIFFERENT DATA SET). A researcher is interested in whether a certain amphetamine drug will affect the retention of learned behavior among rats as a function of how much time is allowed to elapse between the training and the retention test. Four groups, ten subjects in each group, were randomly selected from a colony of Sprague-Dawley rats. All the rats were given the same amount of training on a simple maze. Groups A and C were given the amphetamine, whereas Groups B and D were given a placebo. Groups A and B were tested for retention immediately following the training, whereas Groups C and D were tested 4 hours later. The retention measure consisted of a scaled score based on how many correct responses the rats would exhibit while running the maze, the higher the score the higher the retention FACTOR A Amphetamine Group A Placebo Group B 15 13 9 9 9 12 Immediate 11 7 Test 10 7 6 8 10 10 12 9 14 5 7 11 FACTOR B Group C Group D 1 8 5 6 Delayed 2 9 Test 4 4 5 4 6 5 5 6 2 6 6 6 1 7 -Is the interaction significant?

The F ratio cannot be used on post-facto data.

When the data form is nominal, the appropriate F ratio is