Representing and Processing Qualitative and Discrete Data

1
Representing and ProcessingQualitative and
Discrete Data

• Stats GCSE Chapter 2

2
Tally Charts

• Tally Charts can be used to process data. We can
  then add a frequency column to give the
  totals.
• The whole point of doing a tally is that you only
  go through the data once!
• When doing tally marks, line them up nicely so
  you can spot patterns.

Blue, Green, Blue, Yellow, Red, Green, Brown,
Blue, Yellow, Red, Red, Blue, Green, Yellow,
Brown, Green, Green
Colour Tally Frequency
Blue
Brown
Green
Red
Yellow
3
Cumulative Frequency

• Sometimes it is useful to add a cumulative
  frequency column to our frequency table.
• Cumulative frequency is a running total of the
  frequency.

Matches Freq Cumulative Freq
47 3
48 10
49 18
50 12
51 7
4
Grouping Discrete Data

• We can put discrete data into groups if there are
  a wide range of values.
• The proper name for these groups is classes.
• See example on photocopy
• Ex 2A

5
Variable Class Width / Open-Ended Classes

• The classes for our frequency table do not
  necessarily need to be of equal width.
• If the extreme values of data arent known then
  we can use an open-ended class too.

Books held Frequency
0-29 5
30-34 8
35-39 10
40-44 14
45-49 6
50-59 4
60 - 3
6
Two-Way Tables

• A two-way table is simply a way of presenting
  frequency data about two related categories of
  data.
• These are called bivariate data.

11A 11B 11C 11D Total
Boys 18 16 13 14
Girls 12 17 14 19
Total