# AQA Psychology UNIT 1

- Created by: Louise Gadd
- Created on: 20-05-12 16:02

**Presenting and interpreting bar charts, histograms and frequency polygons...**

**1. BAR CHARTS** - usually used when the data is in categories (nominal or ordinal) or to illustrate the average scores from different samples. It consists of a series of vertical bars of equal width on the x-axis but varying height to indicate the frequency of each category (on the y-axis).

**2. HISTOGRAMS** - useful form of graphical representation that can be used when presenting continuous data on interval or ratio scales of measurement. A histogram consists of a series of vertical bars of equal width to represent each score or group of scores (class interval) presented on the x-axis. The height of each bar on the y-axis represents the frequency of occurance of each score or class interval.

**3. FREQUENCY POLYGONS** - particularly useful technique when it is necessary to compare 2 or more frequency distrubitions. Used as an alternative to the histogram. Can be drawn by linking the midpoints from the top of each bar contained in a histogram.

**MEASURES OF CENTRAL TENDENCY...**

**THE MEAN** - the arithmetic average of a set of data. Calculated by adding all the values together and dividing the total by the number of scores.

advantage:

- makes use of all the available data.
- most powerful of the measures of central tendency available.

disadvantage:

- however…

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