analysing quantitative data

Question 1

What are descriptive statistics?

Answer 1

• ways of analysing quantitative data
• two ways: measures of central dispersion and measures of central tendency

Question 2

What is meant by measures of central tendency? (2m)

Answer 2

• any measure of average value
• in a set of data
• mean, median, mode

Question 3

Mode

Answer 3

• most common number in set of scores
• can be more than one number
• used with NOMINAL data

Question 4

Strength of mode - AO3

Answer 4

• easy to calculate
• less prone distortion by extreme freak scores
• does not take into account all data
• unlike mean
• is highly influenced by extreme freak scores
• as takes into account all data
• (CONTEXT)

Question 5

Limitation of mode - AO3

Answer 5

• not take into account all scores
• may be less accurate
• unlike mean takes into account all data
• may not be useful
• if more than one mode in data
• (CONTEXT)

Question 5

Median

Answer 5

• middle score
• in list of ranked-ordered scores
• if there are 2 central scores add and divide by 2
• used with ORDINAL data

Question 6

Strength of median - AO3

Answer 6

• easy to calculate
• not affected by extreme freak scores
• unlike mean
• is highly influenced by extreme freak scores
• as takes into account all data
• (CONTEXT)

Question 7

Limitation of median - AO3

Answer 7

• not as sensitive as mean
• not use all scores
• less useful results
• (CONTEXT)

Question 8

Mean

Answer 8

• all scores added up
• divide by total number of scores
• used with INTERVAL data

Question 9

Strength of mean - AO3

Answer 9

• most accurate and sensitive measure of CT
• as uses all data sets
• unlike median not take into account all data
• (CONTEXT)

Question 10

Limitation of mean - AO3

Answer 10

• affected by extreme freak scores
• takes into account all scores
• result in misleading interpretations
• (CONTEXT)

Question 11

What is meant by measures of dispersion? (2m)

Answer 11

• based on spread of scores
• how far score varies from mean/average
• range, standard deviation

Question 12

Range

Answer 12

• spread of data
• smallest to largest
• subtract lowest value from highest AND add 1
• used for ORDINAL data

Question 13

Strength of range - AO3

Answer 13

• easy and quick to calculate
• only uses 2 pieces of data
• unlike SD
• is more complicated
• and time consuming to calculate
• (CONTEXT)

Question 14

Limitation of range - AO3

Answer 14

• distorted by extreme freak scores
• as only takes into account highest and lowest scores
• inaccurate range could be achieved
• (CONTEXT)

Question 15

Standard deviation

Answer 15

• measure of spread around mean
• used for INTERVAL data
• higher calculated n.o. = data spread around mean = less consistent = more individual differences
• smaller calculated n.o. = data clustered around mean = more consistent = less individual differences

Question 16

Strength of standard deviation - AO3 - precise

Answer 16

• most precise/sensitive measure of dispersion
• uses all scores
• so more accurate measure of dispersion
• than range only looks at smallest and largest data

Question 17

Strength of standard deviation - AO3 - less distorted

Answer 17

• less easily distorted
• by extreme freak scores
• takes in account distance of each score from mean
• not just distance from highest to lowest like range

Question 18

Limitation of standard deviation - AO3

Answer 18

• more complicated
• more time consuming to calculate
• unlike range is quick and easy