Descriptive Statistics

Question 1

what is a variable?

Answer 1

something that varies

Question 2

what does operationalising variables consist of?

Answer 2

explaining how a specific variable will be measured to represent a certain concept

Question 3

problems with defining variables

Answer 3

1. subjectivity and objectivity
2. testability

Question 4

what are measurements?

Answer 4

a way to describe real life factors by numbers

Question 5

types of measurement scales

Answer 5

nominal
ordinal
interval
ratio

Question 6

nominal scale

Answer 6

category data with no relationship between the number and measured label

Question 7

ordinal scale

Answer 7

data placed in a relative ranking order, where the distances between scores vary

Question 8

interval scale

Answer 8

at equal intervals and measurements along the scale

measures ‘magnitude’ and contains negative values (however zero is not meaningful)

Question 9

ratio scale

Answer 9

interval scale and zero notes absolute absence, e.g., reaction time

Question 10

what are measures of central tendency?

Answer 10

used to represent a group of scores

Question 11

types of measures of central tendency

Answer 11

mean, median, and mode

Question 12

mean

Answer 12

(sum of scores/number of scores)

this can be affected by outliers

Question 13

median

Answer 13

midpoint of data

less affected by outliers, and is the best choice for ordinal data

Question 14

mode

Answer 14

most occurring score

used if data is on a nominal scale and distribution can be bimodal or atypical

Question 15

what are measures of spread?

Answer 15

how much the scores vary

Question 16

types of measures of spread

Answer 16

range, interquartile range, and standard deviation

Question 17

range

Answer 17

tells nothing about the scores between the minimum and maximum

Question 18

interquartile range

Answer 18

measures the spread of the middle 50% of scores, between Q1 and Q3

Question 19

standard deviation

Answer 19

the measure of data variation around the mean, that gives an indication of what happens between the minimum and maximum of a data set

Question 20

the higher the SD, the _________________

Answer 20

larger the spread of scores

Question 21

calculating the standard deviation

Answer 21

1. calculate the mean
2. work out how far each score is from the mean
3. square these deviation scores
4. add up these values
5. divide by the number of scores
6. square root

Question 22

bar graphs

Answer 22

can contain ordinal and nominal data

can be vertical/horizontal, stacked, or histograms

Question 23

histograms

Answer 23

a starting point for data distribution that can be useful for dealing with outliers

Question 24

what do histograms show?

Answer 24

the number of participants with each specific score

Question 25

stem-and-leaf plots

Answer 25

data is in a compact form and shows the size of data subsets

Question 26

box plots

Answer 26

good for summarising and comparing multiple data sets

Question 27

what are box plots able to summarise?

Answer 27

• lower quartile and upper quartile
• median
• minimum
• maximum
• outliers

Question 28

what does Q3-Q1 provide?

Answer 28

the interquartile range

Question 29

how can data be classed as an outlier?

Answer 29

if it is 1.5x the IQR

Question 30

scatterplots

Answer 30

show the relationship between variables