descriptive statistics

Question 1

what is a variable?

Answer 1

something that changes

Question 2

what does operationalised variable mean?

Answer 2

specific statement about how a variable will be measured

Question 3

what are the problems with defining variables?

Answer 3

1. subjectivity vs objectivity
2. testability

Question 4

what are the 4 types of measurement

Answer 4

1. nominal scales
2. ordinal scales
3. interval scales
4. ratio scales

Question 5

how do scales differ in relationship (2)

Answer 5

1. the properties of the numbers
2. the properties of what is being measured

Question 6

what is a nominal scale?

Answer 6

numbers merely label

no relationship between number size and attribute measured

Question 7

what is ordinal scale?

Answer 7

order of size of numbers = order of size of attribute measures

ordered

distance between scores vary

Question 8

what is interval scales?

Answer 8

eqaul intervals on scale = equal intervals in property measured

measure magnitude

zero = no meaning

Question 9

what is ratio scales?

Answer 9

interval scale AND zero means something

Question 10

example of ratio scale

Answer 10

the time taken for ppt to press button

Question 11

example of interval scale ?

Answer 11

degrees celsuis

Question 12

example of ordinal scales?

Answer 12

IQ score

Question 13

example of nominal scales?

Answer 13

numbers on buses

Question 14

what are the measures of central tendency

Answer 14

mean

median

mode

Question 15

what is the mean?

Answer 15

average

add all then divide by how many there is

Question 16

what is the median?

Answer 16

midpoint of the sample after data has been put in order

Question 17

when to use the mean?

Answer 17

if all values are important and valid

Question 18

when to use the median?

Answer 18

if there are outliers

best choice for ordinal data

Question 19

what is the mode?

Answer 19

score that occurs the most

Question 20

when to use the mode?

Answer 20

nominal scale

can be bimodal (two)

Question 21

what are the limitations of using the mode?

Answer 21

1. some data sets have no mode
2. some data sets have more than one mode
3. the mode can be atypical

Question 22

when can you use the mode (4)

Answer 22

nominal
ordinal
interval
ratio

Question 23

when can you use the median (3)

Answer 23

ordinal
interval
ratio

Question 24

when can you use the mean? (2)

Answer 24

interval
ratio

Question 25

what are 3 ways to measures of spread of data?

Answer 25

1. range 2. interquartile range 3. standard deviation

Question 26

what is the range?

Answer 26

difference between highest and lowest number

Question 27

what is 1 problem with the range?

Answer 27

tells us nothing about the scores between the min and max scores

Question 28

what is the interquartile range?

Answer 28

measures the spread of the middle 50% of scores between 1st and 3rd quarters

Question 29

what is standard deviation?

Answer 29

measure of variation around the mean higher the SD = larger spread of scores.

Question 30

what does the standard deviation do?

Answer 30

gives an indication of what is happening between min and max of data set

Question 31

how to calculate the standard deviation?

Answer 31

1. calculate the mean 2. work out how far each score is from the mean 3. square deviation scores 4. sum this 5. sum of scores / number of scores 6. square root the variance

Question 32

what is it called when we mimic the mean in standard deviation

Answer 32

the variance

Question 33

what is a graph?

Answer 33

visual methods of representing data

Question 34

what do graphs do?

Answer 34

indicate patterns within the data

Question 35

why do we use graphs?

Answer 35

1. decide how to analyse our data 2. illustrate findings

Question 36

what are the 4 types of graphs?

Answer 36

1. bar graphs 2. stem and leaf plots 3. box plots 4. scatterplots

Question 37

what is a histogram?

Answer 37

type of bar graph

Question 38

what are stem and leaf plots?

Answer 38

data in a compact form show size of data subsets can have two digits

Question 39

what do box plots summarise? (5)

Answer 39

1. lower and upper quartile 2. median 3. minimum 4. maximum 4. outliers

Question 40

what are scatterplots?

Answer 40

show the relationship between variables

Question 41

what are box plots good for?

Answer 41

comparing more than one data sets

Question 42

why are histograms and stem and leaf plots used? (3)

Answer 42

1. show frequency of values 2. show overall pattern 3. spot outliers

Question 43

why are bar plots used?

Answer 43

data on nominal scale

Question 44

what must be done before running a statistical analysis?

Answer 44

data must be plotted