Question

Is insomnia related to education status?  Researchers at the Universities of Memphis, Alabama at Birmingham, and Tennessee investigated this question in the Journal of Abnormal Psychology (Feb. 2005).  Adults living in Tennessee were selected to participate in the study, which used a random-digit telephone dialing procedure.  Two of the many variables measured for each of the 575 study participants were number of years of education and insomnia status (normal sleep or chronic insomniac).  The researchers discovered that the fewer the years of education, the more likely the person was to have chronic insomnia.

a) Identify the population and the sample.

b) Identify the data collection method.  Are there potential biases in the method used? Explain.

c) What data type are the two variables mentioned in the study description above?

d) What inference did the researchers make?

6. A manufacturer of table saw blades is interested in determining whether a narrower blade will cause less burning of wood when cutting very hard woods, such as maple. To answer this question, engineers obtain 20 similar one-inch-thick hard maple boards. Half (or 10) of the boards are sawed using the new, narrow-style blade, and the other half (or 10) of the boards are sawed using the standard-width blade. All cuts are done at the same feed rate (the rate at which the board is pushed against the blade to make the cut). The engineers then measure the amount of burning (rated on a scale of 1 to 10, with 10 being the worst) on each board.

What are the cases (or observations or subjects) in this study?

7. Allan has a large jar of 10,000 pennies on his desk. Consider all the pennies in this jar to be a population. The mean age of this population of pennies is 25 years, and the oldest penny is from the year 1935. Allan takes a sample of 80 pennies from the jar and finds the mean age of the sample to be 12.5 years.

Which number is the statistic in this example?  How do you know?  

Answer 1