descriptive statistics: measures of central temdency & dispersion

What are the 3 measures of central tendency?

1. Mean

2. Median

3. Mode

What are the 2 measures of dispersion?

1. range

2. standard deviation

✅ mean

• most sensitive as it includes all the scores/values in a data set so is more representative of the whole data

• used most often

❌ mean

• easily distorted by extreme values

✅ median

• Not distorted by extreme scores

• Easy + quick to calculate once the scores are in order

❌ median

• less sensitive than mean bc not all scores are used in calculation

✅ mode

• Easy + quick to calculate

• Useful when data is in categories, e.g., favourite colours in a class.

❌ mode

• Least sensitive measure and often not representative of the whole data set

• When there are several modes, then this is not very useful information

✅ range

• quick + easy to calculate

❌ range

• Only considers the highest and lowest values. If these values are extreme, then the range may be unrepresentative of the whole data set

• Does not tell us whether the scores are closely grouped around the mean or very spread out

✅ standard deviation

• More accurate + precise measurement than the range as it includes all the values within the final calculation

• Tells us whether the scores are closely grouped around the mean or very spread out. The larger the SD, the greater the spread of scores within a data set.

❌ standard deviation

• long and more difficult calculation.

• Can be distorted by extreme values.