Measures of Central Tendency and Spread

Lesson 11.1:

Basic Statistics

Measures of Central Tendency and Spread

Measures of Central Tendency

• Mean

• Median

• Mode

Open Ended

What do you already know about one or more of these terms (Mean, Median, Mode)?

Measures of Central Tendency

• Mean: "average"

• Median: the middle of the data

• Mode: Most common (Most Often)

How to Calculate

• Mean: Add all numbers and divide by how many data points you have.

• Median: Order the numbers least to greatest and find the middle. (If there are two, find the mean of these two.)

• Mode: Find the data value that occurs most often.

Fill in the Blank

Given the data: 3,3,5,7,8,8,8 What is the Mean?

Fill in the Blank

Given the data: 3,3,5,7,8,8,8 What is the Median?

Fill in the Blank

Given the data: 3,3,5,7,8,8,8 What is the Mode?

Measures of Spread

• Range

• Inter-Quartile Range

• Standard Deviation

Open Ended

What do you already know about one or more of these terms (Range, Inter-Quartile Range, Standard Deviation)?

Measures of Spread

• Range: The distance between the highest and lowest data points.

• Inter-Quartile Range: The distance between the lower and upper quartile. 50% of data is here.

• Standard Deviation: The average distance from the mean.

How to Calculate

• Range: Highest - Lowest

• Inter-Quartile Range: Q2 - Q1 (Q1 is the middle of the lower half, Q2 is the middle of the upper half)

• Standard Deviation: USE DESMOS --> type in the data points in a table --> type stdev(x_1)

Match

Given the data: 2,3,3,5,7,8,8,8 identify the following:

• Range

• Inter-Quartile Range

• Upper Quartile (Q2)

• Lower Quartile (Q1)

6

3

8

5

• 6

• 3

• 8

• 5

Reorder

Put the steps to find Standard Deviation in order

• Go to Desmos

• Enter data into a table

• type stdev(x_1)

1

2

3

• 1
• 2
• 3

Fill in the Blank

Given the data: 2,3,3,5,7,8,8,8 find the Standard Deviation.

Round your answer to the nearest hundredth.

***Take a screenshot of your Desmos table to include as part of your answer***

Desmos Tricks

• Always type the data into a table (click the + button then table)

• Mean: mean(x_1)

• Median: median(x_1)

• SD: stdev(x_1)

• Sort a list: sort(x_1)