These are simulated data that are similar to the TipExperiment data. Hypothetical tables
were randomly assigned to receive checks that either included or did not include a drawing
of a smiley face, either from a male or a female server.
tip_expA data frame with 44 observations on the following 3 variables.
genderWhether the server was female or male
conditionWhether the check had a smiley face or not (control)
tip_percentThe size of the tip as a percentage of the price of the meal