It has been suspected that prolonged use of a cellular telephone increases the chance of developing brain cancer due to the microwave-frequency signal that is transmitted by the cell phone. According to this theory, if a cell phone is repeatedly held near one side of the head, then brain tumors are more likely to develop on that side of the head. To investigate this, a group of patients were studied who had used cell phones for at least 6 months prior to developing brain tumors. The patients were asked whether they routinely held the cell phone to a certain ear and, if so, which ear. The 88 responses (from those who preferred one side over the other) are shown in the following table. Do the data provide sufficient evidence to conclude that use of cellular telephones leads to an increase in brain tumors on that side of the head? Use a chi-square test against a directional alternative following the five steps (a-e) in Exercise 10.2.4. Let α = 0.05.

Phone holding side Left 14 Right 19 Right 28 27 Brain tumor side Left Total 33