Measures Of Central Tendency Ed

Measures of Central Tendency “What??”

• Measures of Central Tendency are used to get an overall sense of a group of numbers.

• MEAN-a.k.a. “average”. Add up all the numbers, and divide by how many there are.

Below is a chart displaying how many cars were sold on each day of the week.

• Below is a chart displaying how manycars were sold on each day of the week Day

Sun

Cars 12 Sold

Mon

Tue

Wed

Thur

Fri

Sat

2

4

3

7

5

18

What is the daily average of cars sold for this week?

(12+2+4+3+7+5+18) / 7

Day

Sun

Cars 12 Sold

Mon Tue

Wed Thur Fri

Sat

2

3

18

4

7

5

Around 7 cars sold 51 7 (12+2+4+3+7+5+18) per day on average …Divided by How many cars each How many days day added up In the week

• Median: The middle number in a set of data lined up from smallest to largest. *If there are two middle numbers, just average them together.

• Prices of different shoes at the store.

$ 45 $12

First, re-write the numbers In order

$45 $87 $56 $125 Middle$34 number is “45”. The Median price Is $45

Points scored by Emily per basketball game:

12 15 13 22 13 26 What is the median score per game?

12 13 13 15 22 26 The median is 14 If there’s two middle numbers… (13 + 15) / 2 …just average them 14 together (find the Mean)…

• MODE: The number that appears the most in a set of data. It is possible to have more than one mode, or none at all !!

• A survey asking 15 students, “How many pairs of shoes do you own?”

5,14, 4, 5, 7, 8, 3, 2, 6, 5, 5, 7, 2, 3, 7 Put in order.

2, 2, 3, 3, 4, 5, 5, 5, 5, 6, 7, 7, 7, 8, 14 Looks like “5” happens the most… …”5” is our MODE.

• Check the set of data, find the Mean, Median, and Mode. Pts. Per Game 10 12 14 11 12 15 9

32

10

Pts. Per Game 10 12 14 11 12 15 9

32

10

Do you see one score that “doesn’t belong?”

A number that is “out there” is called an OUTLIER

• Outliers can drastically affect the mean of the data. Pts. Per Game 10 12 14 11 12 15 9

32

10

Find the MEAN of the data, but this time DON’T Include the Outlier.

• The MEAN is not always the best way to get a good idea of the spread of numbers.