Question

ch 20 a veterinarian collects data on the number of times race horses are raced during their career. the researcher finds the average number of races a horse enters is x-bar= 15.3 with a standard deviation of s = 6.8 in a sample of n = 20 horses.
the researcher notices one horse that has raced 45 times. this outlier poses a problem. what should the researcher do?

○ increase the confidence level.
○ choose a z-interval instead of a t-interval since a z-interval is not affected by outliers.
○ \pwc\ results are not accurate.
○ drop the outlier and recalculate sample mean and standard deviation then proceed with a t-interval.

Explanation:

Outliers can significantly affect the mean and standard deviation. When an outlier is present in a small - sample data set (here \(n = 20\)), dropping the outlier and recalculating the sample statistics (mean and standard deviation) is a common practice. This is because the outlier may not be representative of the general population of race - horse race frequencies.

Increasing the confidence level does not address the issue of the outlier's impact on the sample statistics. Both \(z\) - intervals and \(t\) - intervals are affected by outliers as they rely on measures of central tendency (mean) and spread (standard deviation).

Answer:

Drop the outlier and recalculate sample mean and standard deviation then proceed with a t - interval.