L13 - Descriptive Statistics: Measures Of Central Tendency & Measures Of Dispersion

Question 1

Measures of central tendency

Answer 1

• inform us about central values for a data set
• they’re ‘averages’ - ways of calculating typical value for set of data
• incl. mean, mode and median

Question 2

mean

Answer 2

• add all scores in set then divide by total no. of scores
• most accurate measure, takes into account all scores
• can be distorted by single extreme value in the set
• mean may not actually be one of the scores in the set

Question 3

median

Answer 3

• rank all scores in order and take middle value
• if even no. of scores take midpoint of two scores in the middle
• unaffected by extreme scores
• not as sensitive as mean as not all values are used, can be unrepresentative of data if scores are clustered around high and low levels

Question 4

mode

Answer 4

• most frequent value in a set
• unaffected by extreme scores
• tells us nothing about other scores in data set

Question 5

measures of dispersion

Answer 5

• describes data in terms of how spread out or dispersed the data items are

Question 6

Range

Answer 6

• difference between highest and lowest score in data set
• ADD 1 TO ANSWER
• quick and easy to calculate compared to standard deviation
• can be easily distorted by extreme values

Question 7

Standard Deviation

Answer 7

• average amount that each score differs from the mean
• takes into account all scores
• more difficult to count then range and can only be used on interval data