Question

Recall again that Rind & Bordia (1996) investigated whether or not drawing a happy face
on customers’ checks increased the amount of tips received by a waitress at an upscale
restaurant on a university campus. During the lunch hour a waitress drew a happy,
smiling face on the checks of a random half of her customers. The remaining half of the
customers received a check with no drawing (18 points).
The tip percentages for the control group (no happy face) are as follows:
45% 39% 36% 34% 34% 33% 31% 31% 30% 30% 28%
28% 28% 27% 27% 25% 23% 22% 21% 21% 20% 18%
8%
The tip percentages for the experimental group (happy face) are as follows:
72% 65% 47% 44% 41% 40% 34% 33% 33% 30% 29%
28% 27% 27% 25% 24% 24% 23% 22% 21% 21% 17%

This time, you are to perform a “hypothesis test” using the tip data, answering each of
the questions below. For short-answer questions, be brief. However, you must give
enough detail to justify your answers. Single-sentence responses will generally not
suffice, but do not exceed a paragraph for any given answer.

n. What is your decision concerning the null hypothesis? Did you reject or
retain?

Answer 1

Let first sample is for no happy face and second sample is for happy face.

The hypotheses are:

This is one tailed (left) hypothesis.

Enter data in excel.

Click on Data->Data Analysis->t-Test: Two-Sample Assuming Unequal Variances and press enter.

Enter data range of no happy face and happy facein variable 1 and 2 text boxes.

Hypothesized Mean Difference = 0

alpha = 0.05

Click OK.

The output is shown below:

P-value for one tailed test is 0.0649, which is greater than level of significance, 0.05. We cannot reject null hypothesis. Therefore, we will retain null.

We cannot conclude that drawing a happy face on customers’ checks increased the amount of tips received by a waitress at an upscale restaurant on a university campus.