MGMT Disc 3

2

Ashl

2. Hang Up and Drive : Check out this snippet from Family Circle magazine (January, 2009, Liz Plosser): Motorists who talk on a cell phone while driving are 9% slower to hit the brakes, 19% slower to resume normal speed after braking and four times more likely to crash.

From the information given in the article, a reader can conclude that driving on a cell phone is dangerous. It is a distraction that causes drivers to be "9% slower to hit the brakes, 19% slower to resume normal speed after braking, and four times more likely to crash." This information stated is not enough to make a valid conclusion. It is missing a sampling technique, sample size, variation, and confidence intervals. Discluding the sample size leaves their claim unsupported since some sample sizes are too small and do not accurately represent the population. Questions like alcohol toxicity and faulty breaks come to mind. Were the drivers sober? Were all the roads and breaks on the car the same? What kind of analysis method did the authors use? Using a degree of confidence would have made the information more reliable.

Michelle

In order to set up a confidence interval, there are a few criteria that would need to be met initially.  The first step is to ensure that the sample is a random sample of the population. The sample needs to contain enough successes and failures to make it a viable sample.  We need to identify our sample statistic. The next step is to determine the confidence level.  Next we will determine the standard of error using the following formula: SE = sqrt [ p(1 - p) / n ].  The next step is to determine the critical value using t-distribution.  Compute the margin of error. Finally specify the confidence interval. The range of the confidence interval is determined by taking the sample statistic ± margin of error.

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