Effects of Outliers

A value that is much higher or much lower than the other values in a set of data.

• Outlier

• Box Plot

• Range

• Histogram

The data set below has an outlier of 42.

2, 5, 12, 15, 19, 4, 6, 11, 16, 18, 12, 12, 42

What effect does removing the outlier have on the distribution of the data?

• The mean will decrease

• The median will decrease

• The mean will increase

• The median will increase

The data below represent the ages of several people in a class. What effect does Mr. Smith’s age have on the data set? Select ALL that APPLY.

• Mr. Smith’s age increases the range of the data.

• Mr. Smith's age skews the data to the left.

• Mr. Smith’s age increases the mean of the data.

• Mr. Smith’s age increases the median of the data.

• Mr. Smith's age skews the data to the right.

The following values show the lengths of fences a company installed during a week.  Which statement is true?

• The 275-foot fence caused the mean to be significantly lower than the median.

• The 275-foot fence caused the median to be significantly lower than the mean.

• The 2,250-foot fence caused the mean to be significantly greater than the median.

• The 2,250-foot fence caused the median to be significantly greater than the mean.

A data set has an outlier that is significantly higher the expected range. How does including this value affect a plot of the distribution?

• The outlier will flatten the distribution so that it looks uniform.

• The outlier will have no effect on the distribution at all.

• The outlier will negatively skew the distribution.

• The outlier will positively skew the distribution.

Which of the following is NOT affected by outliers?

• mean

• standard deviation

• IQR

• range

• median

Which scenario is most likely to have outliers?

• Ages in a senior citizen community

• Heights of adult males

• Test scores where most are 90% but a few below 50%

• Number of pages in novels

A bowler had the following scores after 5 games: 

196, 205, 197, 280, and 202.

How much does the bowler’s mean score increase if the outlier is considered, compared to if the outlier is not considered?

• 13

• 16

• 19

• 22

If outliers are removed, what measure is more significantly impacted?

• Mean

• Median

Jacob recorded the ages of the people at a picnic. The data set is listed below. 12, 12, 14, 15, 16, 20, 24, 28, 32, 35, 36 What effect does the arrival of Jacob’s 72-year-old grandfather have on the mean age of people at the picnic?

• It increases by about 4.2.

• It increases by about 6.6.

• It decreases by about 4.2.

• It decreases by about 6.6.