An area of research in biomechanics and gerontology concerns falls and fall-related injuries, especially for elderly people. Recent studies have focused on how individuals respond to large postural disturbances (e.g., tripping, induced slips). One question is whether subjects can be instructed to improve their recovery from such disturbances. Suppose researchers want to compare two such recovery strategies, lowering (quickly stepping down with front leg and then raising back leg over the object) and elevating (lifting front leg over the object). Subjects will have first been trained on one of these two recovery strategies, and they will be asked to apply it after they feel themselves tripping. The researchers will then induce the subject to trip while walking (but harnessed for safety) using a concealed mechanical obstacle. Suppose the following 24 subjects have agreed to participate in such a study:

Females: Alisha, Alice, Betty, Martha, Audrey, Mary, Barbie, Anna

Males: Matt, Peter, Shawn, Brad, Michael, Kyle, Russ, Patrick, Bob, Kevin, Mitch, Marvin, Paul, Pedro, Roger, Sam

Question:

What's a way to implement a paired design into the situation noted above. Explain on whether or not there would be any benefits to this paired design. Hint: I suggest using an example that we have seen with two different populations.

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Design your own experiment: Develop the plan for the investigation of a research question that would be best answered using paired data.

a. State the research question.

b. Explain how pairing will be used.

c. Identify the response and explanatory variables.

d. Describe how randomization (random sampling, random assignment, or both) will be used.

e. State the appropriate null and alternative hypotheses in words.

f. Describe when it will be appropriate to use a theory-based method to test the hypotheses stated in part (e).

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Given the three sample proportions 0.25, 0.30, and 0.35, determine the Mean Group Diff statistic.

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Many studies have been done to look at the relationship between heart disease and baldness. In one study, researchers selected a sample of 663 heart disease male patients and a control group of 772 male patients not suffering from heart disease from hospitals in eastern Massachusetts and Rhode Island. Each was asked to classify their degree of baldness. The results are given in the following table. Use these data to answer (a)-(c).

Baldness Total None Little Some Much Yes 251 165 195 52 663 Heart disease No 331 221 185 35 772 Total 582 386 380 87 1,4350.060 0.120 0.180 0.240 Shuffled Mean Group Diffs