Question

logist wants to understand how clinical depression scores dow BDI or high BDID) and test difficulty hol Bndividuals with or assessing whether or not an indimory test. B Individuals with low BDI scores are. The psychologist assesses 40 participants; he r medium, or hard) affect performance on a memory test. The Beck Depression Inventory (BDD is a ether or not an inividual presents the clinical symptoms of depression ed way of assessing whe ot considered to be clinically depressed, and individuals with high BDI scores their er score on the BDI, and then gives them are considered to be clinically depressed. either an easy, medium, or hard memory test. The data are e records easy presented below. Easy Test Mediun Test Hard Test 85 95 95 Low BDI 45 75 85 High BDI Plot these means on means on the axes below as a line graph, with the 'test difficulty' variable on a. Based on how the data looks when graphed, do you think there may be any main or interaction effects?

please answer in complete sentences and explain

Answer 1

This is a simple problem related to plotting the line graph of BDI with respect to the difficulty levels of the tests.

We plot the line graph of the BDI levels on y axis and the test difficulty of the x axis.

The data to be plotted

BDI Vs Test Level	Easy Test	Medium Test	Hard Test
Low BDI	95	85	95
High BDI	85	75	45

100 90 95 70 60 50 40 30 20 10 45 Medium Test Hard Test Easy Test Low BDI High BDI

Now that we have plotted the graph , we now check for main or interaction effects.

But what are these effects?

A main effect is the effect of one of your independent variables on the dependent variable, ignoring the effects of all other independent variables.

while

A statistical interaction occurs when the effect of one independent variable on the dependent variable changes depending on the level of another independent variable.

Now that we know definitions of each, lets try to observe the graph in light of these effects.

We can see that the the difference between the low and high BDI is same for low and medium level tests but it changes drastically for high test .

Thus we can assume that for two tests the interaction effects are observed while for high test there is no interaction effect .

WE cant prophesis any conclusive evidence about the interaction effect hence based on the graph .

Now if we see for main effect then for low BDI then we can set out any pattern (decrease then increase) but for high BDI the pattern is clearly decreasng .

Hence test level has a main effect on high BDI.

but no such pattern for test is seen for low BDI .

if we look at the factor of test for both BDIs then no conclusive main effect can be drawn.