Question

Identify the IV and the DV. Also, describe some variables the researcher should control to eliminate their effects on the result. Please make sure to use complete sentences.

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Studies have shown that drawing a smiling face on a restaurant bill may increase the percentage of a tip left for food servers. A researcher turned the lab into a coffee shop. The participants were invited to the lab and served an express coffee, and then they received a bill with a smiling face or no smiling face from the server (a research assistant). In the end, they were asked to write the percentage of tip that they would like to leave for the server. The data showed that when a smiley face was drawn on the coffee bill, participants left a higher percentage of a tip than when the smiley face was not drawn on the bill.

Answer 1

The researcher wishes to test the claim that drawing a smiling face on a restaurant bill may increase the percentage of a tip left for food servers.

Here, as stated above, the decision whether to tip more or not depends on whether or not a smiley is drawn on the bill. Hence, the Independent variable (IV) would be the categorical variable, with two levels:

Smiley drawn on the Bill - YES or NO

And the dependent variable (DV) would be:

Curtomer tips more - YES or NO

However, before conducting the experiment, the researcher must ensure that there are no confounding variabes in the study. For eg. variables like Age, Gender, Income, etc may affect the DV along with the IV, i.e say, younger people are more likely to tip more on a bill with smiley than others (or) Women may be more likely to tip more on a bill with smiley than men.

Hence, the variables like - Age, Gender, Income etc must be contolled to eliminate their effects on the result.