paper 1 - analysis of data Flashcards
define population
consists of all members in the group being considered
define representative
reflecting the whole population
define discrete data
can take only an exact value
define continuous
data can take any value in a range
define qualititative
descriptive
define quantitative
numerical and may be discrete or continuous
define random sampling
equal chance of being chosen, e.g. drawing names out of a hat
define systematic sampling
a starting point is chosen then every nth is selected
pros of systematic sampling
simpler and quicker
cons of systematic sampling
- may be unrepresentative if theres a pattern
- not equal chance of selection
define quota sampling
population is divided into groups a given number is surveyed from each group
cons of quota sampling
not random
pros of quota sampling
cheap and quick to carry out
define stratified sample
population is divided into quotas then sample is chosen from each category - sample is in proportion to size of each category in population
define convenience sample
could be the first x number of people the interviewer meets
pros of convenience sample
quick and cheap
cons of convenience sample
highly likely the sample is unbiased or unrepresentative
define cluster sample
population is divided into groups or clusters - group is chosen and every item in this group is chosen
pros of cluster sample
a large number of small clusters minimises the chances of being unrepresentative
define opinion polls
large scale opinion polls often use a combination of cluster and quota sampling
pros of opinion polls
not biased
cons of opinion polls
- disadvantage of conclusions drawn from opinion polls is that opinions may change over time
- large population but often based on a small proportion of the population
how to find the interquartile range
IQR = UQ - UQ
advantages of the range
easy to find
disadvantages of the range
affected by extreme values
do not use all of the values of the data
advantages of IQR
not affected by extreme values
disadvantages of IQR
does not use all of the data
may not give a fair comparison if one dataset has more values than the others
advantages of standard deviation
uses all of the data
gives a fair comparison when one dataset has more values than the other
disadvantages of standard deviation
more difficult to calculate
to draw a histogram 2
- subtract class boundary to find class width
- if not equal , divide each frequency by class width to give frequency.
