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Copyright 2009 Pearson Education, Inc.

3.1 Frequency Tables

LEARNING GOAL

Be able to create and interpret frequency tables.

Slide 3.1- 2Copyright 2009 Pearson Education, Inc.

Definition

A basic frequency table has two columns:

One column lists all the categories of data.

The other column lists the frequency of each category,which is the number of data values in the category.

Slide 3.1- 3Copyright 2009 Pearson Education, Inc.

EXAMPLE 1 Taste Test

The Rocky Mountain Beverage Company wants

feedback on its new product, Coral Cola, and sets up a

taste test with 20 people. Each individual is asked to

rate the taste of the cola on a 5-point scale:

(bad taste) 1 2 3 4 5 (excellent taste)

The 20 ratings are as follows:

1 3 3 2 3 3 4 3 2 4 2 3 5 3 4 5 3 4 3 1

Construct a frequency table for these data.

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Slide 3.1- 4Copyright 2009 Pearson Education, Inc.

Solution:

The variable of interest is taste, and this variable cantake on five values: the taste categories 1 through 5.

(Note that the data are qualitative and at the ordinal

level of measurement.)

We construct a table

with these five

categories in the left

column and their

frequencies in the

right column, as

shown in Table 3.2.

EXAMPLE 1 Taste Test

Slide 3.1- 5Copyright 2009 Pearson Education, Inc.

Binning Data

Definition

When it is impossible or impractical to have a category

for every value in a data set, we bin (or group) the data

into categories (bins), each covering a range ofpossible data values.

Slide 3.1- 6Copyright 2009 Pearson Education, Inc.

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Slide 3.1- 7Copyright 2009 Pearson Education, Inc.

Slide 3.1- 8Copyright 2009 Pearson Education, Inc.

Definition

The relative frequency of any category is the

proportion or percentage of the data values that fallin that category:

relative frequency =frequency in category

total frequency

Relative Frequency

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Relative frequency is also called 'proportion.'

N= Frequency Total

N = sum of your frequency = sum of F

You can show relative frequency as a fraction, or you

can change the fraction into a decimal.

Decimals have a sum of 1

Fractions a sum of the total.

You can then change the decimals to percentages

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Slide 3.1- 10Copyright 2009 Pearson Education, Inc.

Definition

The cumulative frequency of any category is the

number of data values in that category and allprecedingcategories.

Cumulative Frequency

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Slide 3.1- 12Copyright 2009 Pearson Education, Inc.

Abbreviated as CF

Think about cumulative frequency in terms of'accumulating' the data. This is not properly expressed in the

textbook.

Pay close attention to how the data is organized.

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Slide 3.1- 13Copyright 2009 Pearson Education, Inc.

The End

Grade F RF CF

A 4 4/24 = 0.167 4 4/24*100 = 16.67%

B 7 7/24 = 0.292 11 7/24*100 = 45.83%

C 8 8/24 = 0.333 19

D 3 3/24 = 0.125 22

F 2 2/24 = 0.083 24

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