CentralTendency

The Three “M”sMean

MedianMode

MeanFirst, __________ the data values. ADDThen __________ by the numberof data items.

DIVIDE

MedianFirst, the data values need to bearranged _____ __________. in order

Then find the _____________ number.middleIf there is an _________ number of data...even

You ________ the TWO middle numbersaddand __________ by ___.divide 2

ModeThe data item or items that occurthe __________ often.most

RangeFind the _____________ betweenthe lowest and highest value.

difference(not a central tendency)

Example#1

4, 7, 8, 2, 1, 2, 4, 2Mean: Add them all up and divide

by how many you have4+7+8+2+1+2+4+2=3030÷8 =3.75

That is the mean!Often referred to as the “average”

4, 7, 8, 2, 1, 2, 4, 2Median: Put them in order.

Find the middle.

1 2 2 2 4 4 7 8Oh no!

Add them together and divide by 2.

2+4=6÷2=3That isyour

median!

4, 7, 8, 2, 1, 2, 4, 2Mode: MOST often

Look at your list from the median

1 2 2 2 4 4 7 8Which occurs the MOST often?

That makes 2 the MODE

4, 7, 8, 2, 1, 2, 4, 2Range: Subtract the highest and

lowest values.

1 2 2 2 4 4 7 88- 17 That is your range

EXAMPLE#2

5,8,13,12,7,4,8Mean: Add them all up and divide

by how many you have5+8+13+12+7+4+8=5757÷7 =8.142857

Round to the TENTH

8.1

5,8,13,12,7,4,8Median: Put them in order.

Find the middle.

4 5 7 8 8 12 138 That is your

median!

5,8,13,12,7,4,8Mode: MOST often

Look at your list from the median

4 5 7 8 8 12 13Which occurs the MOST often?

That makes 8 the MODE

5,8,13,12,7,4,8Range: Subtract the highest and

lowest values.

13- 49 That is your range

4 5 7 8 8 12 13

OutlierKnown as an “_______________” value. extremeValue(s) that are too _______or too _______.

highlow

Determine the outlier in each set of dataand its effect on the data

88, 90, 55, 94, 89#1The outlier will make the data decrease

16, 64, 88, 73, 57#2The outlier will make the data decrease

46, 64, 58, 53, 98#3The outlier will make the data increase

Determine the outlier. Then determine its affect on the mean, median, and mode.

7, 9, 30, 9, 5, 6The outlier will make the data

increase

7, 9, 30, 9, 5, 6Without the outlier

(take out the outlier) With the outlier (as

is)

Mean

7 + 9 + 9 + 5 + 6

= 36÷ 5 = 7.27.2

7 + 9 + 30 + 9 + 5 + 6= 66÷ 6 = 11

11The outlier (30) ___________ themean by _____

INCREASES3.

8( 11 - 7.2 = 3.8)

7, 9, 30, 9, 5, 6Without the outlier

(take out the outlier) With the outlier (as

is)

Median

5 6 7 9 97

5 6 7 9 9 307 + 9= 16÷2 = 8

8The outlier (30) ___________ themedian by ___

INCREASES1 ( 8 - 7 = 1)

7, 9, 30, 9, 5, 6Without the outlier

(take out the outlier) With the outlier (as

is)

Mode

5 6 7 9 9

95 6 7 9 9 30

9The outlier (30) _____________ the mode

does not change