Quartiles, IQR, Outliers

What is the Median

• Middle number (also known as Q2)

• the average

• the number that occurs the most

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

• Outlier
• Box Plot
• Range
• Histogram

When using IQR to find outliers, which formula will identify the upper limit?

• Q3 - 1.5(IQR)

• Q1 + 1.5(IQR)

• Q1 - 1.5(IQR)

• Q3 + 1.5(IQR)

When using IQR to find outliers, which formula will identify the lower limit?

• Q3 - 1.5(IQR)

• Q1 + 1.5(IQR)

• Q1 - 1.5(IQR)

• Q3 + 1.5(IQR)

Which of the following best describes the process of finding the interquartile range for a set of data?

• Add the biggest and smallest numbers.
• Place the numbers in order from least to greatest and find the middle.
• Find the difference between the maximum and the minimum.
• Subtract Q1 from Q3.

A data set contains only one outlier. Which statistical measure will most likely remain the same if the outlier is removed?

• Mean
• Mode
• Range
• Standard deviation

What do you do if there are two numbers in "the middle" when you are finding the median?

• Pick your favorite number
• Add the two numbers in the middle & then divide by two.
• They are both the median
• None of the above

What measure of central tendency (mean, median or mode) would be best for the following set of data?
20, 89, 92, 97, 99, 100

• Mode, because it is the one that shows up the most.
• Median, because there is an outlier.  The outlier would influence the mean too much.

• Mean, because there is not an outlier.  You should always use the mean.
• There is not a best measure of central tendency for this data.

What measure of center is best to use when we have outliers?

• mean

• median

• mode

• range

The __________ of the data set is the sum of the data divided by the number of pieces of data.

• third quartile

• mean

• measures of center

• mode