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# Unit 4, Day 3 - PowerPoint PPT Presentation

Unit 4, Day 3. SWBAT determine the best measure of central tendency to represent a set of data. Vocabulary. CENTRAL TENDENCY : describes/summarizes the center of a data set. Mean, median, mode OUTLIER: something that is very different from everything else \$0.05, \$123.00, \$124.00, \$130.00.

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### Unit 4, Day 3

SWBAT determine the best measure of central tendency to represent a set of data

• CENTRAL TENDENCY: describes/summarizes the center of a data set.

• Mean, median, mode

• OUTLIER: something that is very different from everything else

\$0.05, \$123.00, \$124.00, \$130.00

We are looking for a measure(s) that is close to MOST of the data

• Check for a mode, if there is NOT a mode, it cannot be a good measure

• Eliminate “mode” as a possible answer

• If the mode is an outlier, it is not a good measure

• 1, 1, 68, 69, 70, 74

• Eliminate “mode” as a possible answer

• Examine the data for outliers. If there are outliers in only one direction, the mean will not be a good measure.

• 1, 100, 105, 110, 110, 111

• 1, 100, 105, 110, 110, 111, 2000

• If these rules do not apply, then any measure of central tendency can be used to represent the data

• The mode

• The mean

• The mode and the median

• The median

Mean actually is about 121… so you can see that’s not the best measure

Order numbers

Is there a mode?

No, eliminate

Are there outliers?

Yes, eliminate

mean

• Is there a mode? No – eliminate it

• Is there an outlier? Yes, football coaches make a lot more money

• In one or two directions? One – eliminate mean

• The median is the only measure that represents most salaries. There is no mode, and the outlier causes the mean not to be representative

• Order the numbers first

• Rule 1: No mode – eliminate (A and C)

• Rule 2: There is no mode, so it is not an outlier

• Rule 3: No outliers

• Best choice is D.

3. 3, 16, 17, 17, 18, 18

• Order the numbers first

• Rule 1: Yes, mode is 18

• Rule 2: The mode is not an outlier

• Rule 3: Three is an outlier, eliminate mean

• I chose median and mode. I eliminated mean because there is an outlier of 3.

• Put all of the sets in order from least to greatest

• If there’s a mode, identify it

• If there’s an outlier, identify it.

• D.

• No mode, and there’s an outlier (not mean)

• D.

• No mode, and no outliers (keep mean)

• D.

• Mode is 7, no outliers (keep mean)

• Mode, mean, median all work

• Mode is not an outlier, no other outliers

• Mean, and median

• No mode, and no outliers

• Mean is NOT good because 1000 is an outlier

• A

• Possibly D because the 20 isn’t quite far enough away to be a real outlier

• B. the mean is NOT a good measure because 5 is an outlier

• All measures of central tendency work, there is a mode and there are no outliers

• Mean and median are best, but you could also include mode because it’s not an outlier