Which factors are relevant to the time a consumer spends looking at a product on the shelf prior to selection? An article reported the following data on elapsed time (sec) for fabric softener purchasers and washing-up liquid purchasers; the former product is significantly more expensive than the latter. The products were chosen because they are similar with respect to allocated shelf price and number of alternative brands. fabric softener- same size= 15, sample mean=30.47, sample sd=19.15; washing up liquid- sample size=19, sample mean=26.53, sampld sd=15.37.
a) What if any assumptions are needed before the t inferential procedure can be used to compare true average elapsed times?
b) Carry out a test of hypotheses to decide whether the true avg difference in elapsed times differs from zero.