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4. Resistance training is a popular form of conditioning aimed at enhancing spor

ID: 3362282 • Letter: 4

Question

4. Resistance training is a popular form of conditioning aimed at enhancing sports performance and is widely used among high school, college, and professional athletes, although its use for younger athletes is controversial. Researchers obtained a random sample of 4296 patients between the ages of 8 and 30 who were admitted to U. S. emergency rooms with injuries classified by the Consumer Product Safety Commission code "weight-lifting." These injuries were further classified as " accidental" if caused by dropped weight or improper equipment use. Of the 4296 weight-lifting injuries, 1513 were classified as accidental.

What is a 98 % confidence interval for the proportion of weight-lifting injuries in this age group that were accidental?

The 98 % confidence interval is from ? to ? (Round to 3 decimal places.)

The sample proportion ispˆ=Xnp^=Xn, whereXis the number of "successes" (here, an accidental injury). The standard deviation ofpˆp^isp(1p)n.p(1p)n.The confidence interval based on the sample proportion ispˆ±z pˆ(1pˆ)n,p^±z p^(1p^)n,wherez* is determined by the level of confidence. We usepˆp^in the standard error as our "best guess" of the truep.

The sample proportion ispˆ=Xnp^=Xn, whereXis the number of "successes" (here, an accidental injury). The standard deviation ofpˆp^isp(1p)n.p(1p)n.The confidence interval based on the sample proportion ispˆ±z pˆ(1pˆ)n,p^±z p^(1p^)n,wherez* is determined by the level of confidence. We usepˆp^in the standard error as our "best guess" of the truep.


Explanation / Answer

The statistical software output for this problem is:

One sample proportion summary confidence interval:
p : Proportion of successes
Method: Standard-Wald

98% confidence interval results:

Hence,

98% confidence interval will be:

(0.335, 0.369)

Proportion Count Total Sample Prop. Std. Err. L. Limit U. Limit p 1513 4296 0.35218808 0.0072875183 0.33523478 0.36914138
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