Cumulative frequency & ogives

January 19, 2018 | Author: Anonymous | Category: Math, Statistics And Probability, Statistics
Share Embed Donate


Short Description

Download Cumulative frequency & ogives...

Description

CUMULATIVE FREQUENCY AND OGIVES

1

AS 10.4.1 (a) Collect, organise and interpret univariate numerical data in order to determine measures of dispersion, including quartiles, percentiles and the interquartile range AS 11.4.1 (a) Calculate and represent measures of central tendency and dispersion in univariate numerical data by drawing Ogives 2

Ogives • The word ogive is used to describe various smooth curved surfaces. • S-shaped. • Cumulative frequency curve.

3

Cumulative Frequency Table • In a frequency table you keep count of the number of times a data item occurs by keeping a tally. The number of times the item occurs is called the frequency of that item. • In a frequency table you can also find a ‘running total’ of frequencies. This is called the cumulative frequency. It is useful to know the running total of the frequencies as this tells you the total number of data items at different stages in the data set. 4

Cumulative Frequency Table showing the marks obtained by students in a test Mark

Frequency

Cumulative frequency

This tells you that

1

1

1

1 students scored 1 mark

2

3

3+1=4

4 students scored marks of 2 or less

3

4

4+4=8

8 students scored marks of 3 or less

4

6

6+8=14

5

9

9+14=23

6

11

11+23=34

7

15

15+34=49

8

18

18+49=67

9

10

10+67=77

10

5

5+77=82

Total

82

Check that the final total in the cumulative column is the same as the total number of students

5

Activity 1 1. b) 34 learners c) 82 – 34 = 48 learners d) 77 learners 2. a) Number of pets frequency Cumulative frequency

b) i) 23 learners ii) 3 learners iii) 25 learners

0 8 8

1 6 14

2 6 20

3 3 23

4 2 25

5 1 26

6

A cumulative frequency table can be drawn up from: • Ungrouped data (see page 3) • Grouped discrete data (see page 4) • Grouped continuous data (see page 5)

7

Activity 2 – question 1 Height, h, in cm

Freq

Cum. Freq.

90
View more...

Comments

Copyright � 2017 NANOPDF Inc.
SUPPORT NANOPDF