What are statistics?

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Let's take a closer look at these three interesting questions from various sources, which you can draw on for your final responses.

RESPONSE:

1. What are major quantitative design types? Name at least three types and provide a published example of a study for each type.

Three examples are as follows:

(a) In the simplest experiment, a time series, one or more measurements are taken on all subjects before and after a treatment. A special case of the time series is the so-called single-subject design, in which measurements are taken repeatedly (e.g., 10 times) before and after an intervention on one or a few subjects (Hopkins, 2000).

An example of a study: Bobrovitz, C.D., & Ottenbacher, K.J. (1998). Comparison of Visual Inspection and Statistical Analysis of Single-Subject Data in Rehabilitation Research." Journal of Engineering and Applied Science 77(2), 94-102.

Another study: Chen, C.W. & Ma, H.H. (2007). Effects of the treatment of disruptive behaviors: A quantative synthesis of single subject designs using the PEMS Approach. The Behavior Analyst Today, 8(4), 380-397.

(b) The crossover design addresses the drawbacks of the time series design. For example, in this design, the subjects are normally given two treatments-the real treatment and a control or reference treatment. In this design, half the participants receive the real treatment first, the other half the control first. Then, after a time lapse that is sufficient to allow any treatment effect to wash out, the treatments are then crossed over. The idea here is that any effect of retesting or of something that occurred between the tests can then be subtracted out by an appropriate analysis. Crossover designs are an example of a repeated measures design. Many disciplines use crossover designs, such as psychology, pharmaceutical science, education, and health-care, including medicine. (Hopkins, 2000).

Cross-over designs: Example

? Treatments: Impermeable (IP) / Semi-Permeable (SP)
? Outcomes: Skin temperature, heat storage, oxygen consumption
? Protocol:
- 6 men studied under both types of clothing.
- 3 men randomized to order (IP, SP), 3 men to (SP, IP) (Rissanen & Rintamaki, 1997).

More specifically, the authors ?examined the effects of long term cold exposure on thermal responses and physical performance in men while wearing nuclear, biological and chemical (NBC) protective clothing. The sample of six healthy men performed 60min work/60min rest cycles during 8 hours at an ambient temperature of-10 C. The participants worked by stepping on a 20cm high bench 15 - 1 times min. Using a cross over design, the participants were tested while wearing two different types of NBC clothing: impermeable rubber suit (IP) or semipermeable charcoal impregnated suit (SP) with cold weather underwear layers, as well as rubber gloves, boots and a . full-face mask. They found that both types of NBC protective clothing could be used for long periods in cold conditions at a ...