Scatter graphs and averages

Scatter graphs and averages

Learning objectives

• To describe the correlation relationship in scatter graphs

• Calculate mean

• Calculate Mode

• Calculate median

• Calculate range

Scatter graphs

A scatter plot (aka scatter chart, scatter graph) uses dots to represent values for two different numeric variables.

Scatter graphs

• We describe the relationship in scatter graphs as correlation

• Strong positive correlation

• Weak positive correlation

• Strong negative correlation

• Weak negative correlation

• No correlation

Multiple Choice

What is the correlation of this graph?

• Strong negative correlation

• No correlation

• Strong positive correlation

Multiple Choice

What is the correlation of this graph?

• Weak positive

• Moderate/ weak negative

• No correlation

Multiple Choice

What is the correlation of this graph

• Positive

• Negative

• No correlation

Predicting trends

We are going to look at the icecream sales scatter graph again.

Poll

Would it be easy to estimate the amount of ice cream sales at  $70\degree F?$  

• Super easy 

• Not sure 

• Very tricky 

Line of best fit

We use lines of best fit to help us predict future results.

Multiple Choice

Which do you think is the line of best fit?

• Red

• Blue

• Green

A line of best fit

• Line of best fit refers to a line through a scatter plot of data points that best expresses the relationship between those points.

• Using the line of best fit can you predict sales at

   $70\degree F$  easier?

Averages

mean, median, mode, range

Mean

• This is where we add the data together and divide by the number of data we had to begin with.

• Shoe sizes: 4, 5, 6, 3, 7

• The mean is  $\frac{4+5+6+3+7}{5}$  

• This equals 5 so the mean is 5. 

Multiple Choice

Calculate the mean of: 2, 5, 6, 3, 4

• 20

• 4

• 5

Median

• The median is the data value in the middle of the data once it has been placed in numerical order

• If there is an even number of data you have to take the 2 in the middle add them together and divide by 2. An odd set of data just takes the value in the middle.

• 2, 4, 6, 7 The median of this data is:

•  $\frac{4+6}{2}=5$  so the median is 5.

Multiple Choice

What is the median of this data? 4, 6, 7, 8, 9, 10, 11

• 8

• 8.5

• 7.5

Multiple Choice

What is the median of this data? 4, 5, 6, 7, 9, 10

• 12

• 7

• 6.5

Mode

• Mode is the most popular data

• 3, 5, 5, 6, 7, 5

• We can see 5 is the number that appears the most so 5 is the mode.

• If 2 numbers are equally popular then it is bimodal.

• If several numbers have the same amount it is multimodal

• If the most popular is 0 then it has no mode.

Multiple Choice

Whats the mode? 4, 5, 6, 6, 7, 4, 4, 3, 6,

• 6

• 4

• 5

Range

• The range is largest piece of data takeaway the smallest piece of data.

• 1, 4, 5, 6, 8, 9,

• The range would be 9-1=8

• The range equals 8.

Multiple Choice

What is the range of this data? 4, 6, 7, 8, 10, 12

• 8

• 6

• 2

All done!

You have quizziz to complete this week.

Raise your grade

Q & A on Wednesday.