Ratios & Percents• To help us understand the data, calculate

ratios for:– Infected to uninfected– Infected to total– Uninfected to total

• Use those ratios to create percents for each of the three values

• Make sure you write down what the numbers are in your journal

• Do it neatly, so you can come back to it tomorrow & Friday and know exactly what those numbers are, how you calculated them, and what they mean.

Mean, Median, Mode, and Range

New Objectives!

Content Objectives• SWD understanding of central

tendency by calculating mean, median and mode of shrimp data set.

Language Objectives• SWD evaluation of central tendency

by creating a graph comparing data sets.

Vocabulary

meanmedianmoderangeoutlier

Insert Lesson Title Here

Measure of central tendency are used to describe the middle of a data set. Mean, median, and mode are measures of Central Tendency.

An outlier is a value that is either far less than or far greater than the rest of the values in the data.

21, 21, 28, 29, 30, 28, 32

mean: 21 + 21 + 28 + 29 + 30 + 28 + 32 = 189Add the values.

Divide by 7, the number of values.1897

= 27

median: 21 21 28 28 29 30 32 Order the values.

mode: Two values occur twice.

The median is 28.

21, 28

Find the mean, median and the mode of the data set.

range: 32 – 21 = 11

45, 32, 22, 37, 45, 41, 37

mean: 45 + 32 + 22 + 37 + 45 + 41 + 37 = 259Add the values.

Divide by 7, the number of values.2597

= 37

median: 22 32 37 37 41 45 45 Order the values.

mode: Two values occur twice.

The median is 37.

37, 45

Find the mean, median and the mode of the data set.

range: 45 – 22 = 23

When is one measure more appropriate or more useful than

another?

• When data are in categories, mode can be very helpful & representative

• Mean is best for continuous data (not categories), like rainfall

• Outliers affect mean, so median is often used when outliers are present– Example: salary & financial data

When is one measure more appropriate or more useful than

another?• Look over the shrimp data

– Calculate mean– Find median– Find mode(s)– Find range

• Which one do you think represents the data better, and why?

• Are there outliers? If so, which measures do they affect the most?

Prep for tomorrow

• How do you find the percent of something?

• What kinds of graphs can you create with the data?