Information for the question:

GRAT - Gratuity Amount (coded as 1, 2, 3, 4, or 5) where 1 = <10%; 2 = 10-12%; 3 = 12-14%; 4 = 15-16%; 5 = >18%.

(GRAT was directly measured from customers' payments for the checks).

SVBAR - Several Bartenders in Attendance (0=No; 1=Yes).

(For customers on Tuesday, this variable was coded as 1. For customers on Wednesday, this variable was coded as 0).

IND - # of Individuals in the Party.

(The primary server noted the number of individuals on the meal check).

SMILES - # of Smiles server shared with any one individual in the party.

(This variable was harder to measure because on Tuesday multiple bartenders could have smiled multiple times. It was the primary bartender's responsibility to check with the other bartenders how many times they smiled at any one customer in the party. The primary bartender then noted that number on the meal check).

GENDER - Male or Female Making the Payment (1 = Male; 2 = Female).

(Again it was the primary bartender's responsibility to note the gender of the customer making the payment).

TRIPS - # of Trips in the last Month to the restaurant by the person making the payment.

(This was the only question that the customer was asked to answer. Each check was accompanied by a little card with the question, "How many times in the last month have you visited the restaurant for lunch or dinner?" The bartender bringing the check requested that this question be answered by the individual paying the check).

Question 1: You conducted a regression analysis with GRAT as the dependent variable and SMILES as the independent variable. The R2 is .53, the coefficient associated with SMILES is .43 and its t-statistic is 12.84. You then conducted a regression with all the independent variables in the equation. The coefficients and t-stats are as follows: IND (.23; 2.58); SMILES (.25; 5.445); TRIPS (.01; .12); SVBAR (.98; 4.01); GENDER (-.08; -.38). Which of the statements are true?

(a) TRIPS, SMILES, SVBAR in the multiple regression are significant

(b) It is strange the SMILES has dropped from .43 to .25

(c) It is not strange that GENDER can be insignificant in a multiple regression setting and significant in the bivariate setting

(d) You can confidently say that the idea to be customer-friendly by attentive service is a good one in this context.

(e) a, c, and d are true