# GCSE Statistics Chapter 3 Summary- Representing and Processing Continuous Data

After completing this chapter, you will be able to;

- Select suitable class intervals
- Draw and interpret pie charts, frequency diagrams, stem and leaf diagrams, population pyramids, choropleth maps and histograms with equal and unequal class intervals
- Understand the terms ‘symmetrical’, ‘positive skew’ and ‘negative skew’, and be able to identify such distributions
- Recognise features that make graphs misleading.

- Created by: Lottie_Anderson
- Created on: 08-12-12 11:49

First 342 words of the document:

Frequency tables, pie charts and stem and leaf diagrams

1.) Continuous data can be sorted into a frequency table. The class

intervals must not have gaps in between them or overlap each other.

2.) All possible values that round to the same number must fit into the same class

interval.

3.) Intervals do not need to be of equal width. Use narrower intervals where the

data is grouped together and wider intervals where the data is spread out.

4.) Pie charts can be used to show continuous data. The area of each sector

represents the frequency for that class interval. Other than this the chart is drawn

the same way as for discrete data.

Cumulative frequency diagrams

5.) If there are not too many observations they can be treated as individual

numbers and shown as a stem and leaf diagram. The stem shows the first

digit(s) of the numbers and the leaves show the last digit.

6.) Cumulative frequency is a running total of frequencies.

7.) Cumulative frequency diagrams can be used to estimate or predict other

values.

Histograms and frequency polygons

8.) A histogram is similar to a bar chart but, because the data is continuous,

there are no gaps between the bars.

9.) A frequency polygon joins the midpoints of the top of the bars with straight

lines.

10.) A histogram shows how the data is distributed across the class intervals.

11.) A distribution can be symmetrical, have positive skew or negative

skew.

12.) To draw a histogram for unequal class intervals you need to adjust the

heights of the bars so the area is proportional to the frequency.

13.) The height of the bar, called the frequency density, is found by dividing

the frequency by the class width.

14.) The frequency density and the width of the class interval are used to work

out the frequency of each class interval in a histogram.

Frequency = Frequency Density X Class Width

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