Right or left

1.3.17 Most people are right-handed, and even the right eye is dominant for most people. Molecular biologists have suggested that latestage human embryos tend to turn their heads to the right. In a study reported in Nature (2003), German bio-psychologist Onur Gntrkn conjectured that this tendency to turn to the right manifests itself in other ways as well, so he studied kissing couples to see which side they tended to lean their heads while kissing. He and his researchers observed kissing couples in public places such as airports, train stations, beaches, and parks. They were careful not to include couples who were holding objects such as luggage that might have affected which direction they turned. For each kissing couple observed, the researchers noted whether the couple leaned their heads to the right or to the left. They observed 124 couples, age 13-70 years. Suppose that we want to use the data from this study to investigate whether kissing couples tend to lean their heads right more often than would happen by random chance.

a. Define the parameter of interest in the context of the study and assign a symbol to it.

b. State the null hypothesis and the alternative hypothesis using the symbol defined in part (a).

c. Of the 124 kissing couples, 80 were observed to lean their heads right. What is the observed proportion of kissing couples who leaned their heads to the right? What symbol should you use to represent this value?

d. Determine the standardized statistic from the data. (Hint: You will need to get the standard deviation of the simulated statistics from the null distribution.)

e. Interpret the standardized statistic in the context of the study. (Hint: You need to talk about the value of your observed statistic in terms of standard deviations assuming ______ is true.)

f. Based on the standardized statistic, state the conclusion that you would draw about the null and alternative hypotheses.