Below are data showing the results of six subjects on a memo

Below are data showing the results of six subjects on a memory test. The three scores per subject are their scores on three trials (a, b, and c) of a memory task. Are the subjects getting better each trial? Test the linear effect of trial for the data in the table below.

a. Compute L (linear effect of trial) for each subject using the contrast weights -1, 0, and 1. That is, compute (-1)(a) + (0)(b) + (1)(c) for each subject. Make a new column in your table with this result.

b. Compute a one-sample t-test on this column (with the L values for each subject) you created.

HINT: See the example in the “Specific Comparisons” section of Chapter-12. Find the “t-value” and the “two-tailed probability” using the EXCEL “TDIST” function. Assume the statistic for this problem is “L” and use the following formula for the t-value. Also assume the hypothesized value is 0, since the contrast weighting (-1,0,+1) for a “perfect” set of data would make “L” be 0 in all cases.

t = (statistic – hypothesized value) / (standard error of the statistic)

t = (Mean of L – 0) / (Standard Error of L)

t-value = t = (x(bar)/s)/sqrt(n)

X = Sample Mean

S = Sample Standard Deviation

N = Number of L-Samples

Solution