Descriptive Statistics

Question 1

Mean

Answer 1

This is where all the scores are added up and then divided by the number of scores.
> It is used when there are no extremes of data (unusually high or unusually low scores).

Question 2

Dis/Advantages of Mean

Answer 2

+ Very sensitive measure.
+ Takes into account all of the data and so is a very powerful measure.

• Can be misleading if there are extreme scores (the odd unusually high, or low score).
• Often the mean score is not one of the original scores. It may involve decimal points.

Question 3

Median

Answer 3

• This is the central score.
• Worked out by arranging the scores in numerical order.
• Then finding the middle number
  > u know

Question 4

Dis/Advantages of Median

Answer 4

+ Not affected by extreme scores.
+ Easier to work out than the mean.

• Not as sensitive as the mean as not all of the raw scores are taken into account.
• Not representative of the scores obtained, especially if there are only a few scores.

Question 5

Mode

Answer 5

• This is the most frequently occurring score

> Used when there are a limited number of data scores or when the data is nominal (category data).

Question 6

Dis/Advantages of Mode

Answer 6

+ Unaffected by extreme scores.
+ Easy to work out.

• Often there is more than one mode, and often there is no mode.
• The mode can be unreliable, often giving an inaccurate picture of the data set.

Question 7

Standard Deviation

Answer 7

• The measure of spread of scores from the mean.

- The larger the standard deviation, the larger the spread of scores from the mean.

Question 8

Dis/Advantages of Standard Deviation

Answer 8

+ More sensitive measure of dispersion than the range and interquartile range since all scores are used in its calculation.
+ Describes the spread of scores with great precision.

• It is complicated to calculate.
• It is less meaningful if the data aren’t normally distributed.

Question 9

Range

Answer 9

• This is the difference between the highest and the lowest score.

Question 10

Dis/Advantages of Range

Answer 10

+ It is quick and easy to work out.
+ Takes into account the full spread of the data.

• It can be affected by extreme scores.
• Doesn’t take into account the full data set, only looking at the highest and lowest number.