# GCSE Statistics Chapter 4 Summary- Summarising Data

After completing this chapter, you will be able to;

• Work out measures of central tendency;
• Find the mean, mode and median of raw data given as a list or as a frequency distribution
• Estimate the mean and median of a grouped frequency distribution and identify the modal class
• Understand the effects of transformations of data on the averages
• Understand when each of these averages is appropriate
• Calculate the weighted mean
• Work out measures of dispersion;
• Work out the range of data given as a list or frequency distribution
• Work out quartiles and percentiles
• Draw box plots
• Identify outliers
• Calculate and use variance and standard deviation
• Compare distributions of data
• Use simple index numbers, chain base index numbers and weighted index numbers;
• Know about the retail prices index.
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## Pages in this set

### Page 1

Averages

1.) An average is a single value used to describe a set of data.

2.) The mode is the value that occurs most often.

3.) The median is the middle number in a list after the numbers have been put in
order.

4.) When the number of data values,…

### Page 2

12.) Range = largest value ­ smallest value

13.) The lower quartile is the value such that one quarter (25%) of the values
are less than or equal to it.

14.) The upper quartile is the value such that three quarters (75%) of the values
are less…

### Page 3

A friendlier formula for variance is
Var(x)= x12 + x22 + x32 +...+ xn2
n

26.) The standard deviation is the square root of the variance.
Standard deviation (SD) = R(x mean)2/n

Comparing data sets

27.) A full comparison need, at least, both a measure of central tendency and
a…