In testing the reliability of DNA results used in crime labs, the new procedure

Question

In testing the reliability of DNA results used in crime labs, the new procedure matched DNA results to suspects 46 out of 50 times.

Obviously for the purpose of convincing juries the labs like to how a 99% success rate.

State a +4 99% confidence interval for the proportion of results that are matched successfully:

We are 99% sure the that this new DNA match procedure correctly identifies susspects between ______ % and _____% of the time.

Using the same sample, is there evidence at the .01 level that this procedure will successfully match DNA results 99% of the time?

Ho: p ____ 99% Ha: p ____ 99%

z =

p =

State your conclusion: There ______(is/is not) statistically significant evidence at the .01 level that this new procedure will match DNA results 99% of the time.

Explanation / Answer

We are 99% sure the that this new DNA match procedure correctly identifies susspects between 82 % and 100 % of the time.

Ho : p = 99% Ha: p not = 99%

z = -4.97

p value = 0.000

There is not statistically significant evidence at the .01 level that this new procedure will match DNA results 99% of the time.

Test and CI for One Proportion

Test of p = 0.99 vs p not = 0.99

Sample X N Sample p 99% CI Z-Value P-Value
1 46 50 0.920000 (0.821174, 1.000000) -4.97 0.000

Using the normal approximation.
The normal approximation may be inaccurate for small samples.

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