Sampling & Data Collection Flashcards
what is qualitative data
data given in words to describe something
what is quantitative data
data given in numbers which count or measure something
what is discrete data
quantitative data that needs to be counted
what is continuous data
quantitative data that needs to be measured
what is population
the group of people or things you wish to find out about
what is finite population
a population where you can count how many members there are
what is infinite population
a population where it is impossible to determine how many members there are
what is a survey
a method by which you find out about the population
what is a census
a survey involving all of the population
what is sample
a small section of the population that have been chosen for a survey
what is a sampling unit
an individual member of the population
what is a sampling frame
a full list if the sampling units in the population
give 1 advantage of a census
it gives fully accurate results
give 2 disadvantages of a census
it is time-consuming and expensive
give 3 advantages of sampling
It is quicker, cheaper and less data is needed to be analysed
give 2 disadvantages of sampling
it might not represent the population accurately, and it could be biased
how is simple random sampling carried out
every member of the population is uniquely numbered. Different numbers are randomly selected using a random number generator
what is simple random sampling
every member of the population has an equal chance of being selected
what is systematic sampling
a repetitive system used to select a sample from the population
how is systematic sampling carried out
- carry out size of the interval:
size of population / size of
sample - choose a starting point between 1 and then select every kth member after the first one
what is stratified sampling
the population is split into groups and a proportional representation of the different groups is selected
how is stratified sampling carried out
the number of members sampled from a stratum =
(size of sample / size of population) * number of members in the stratum
what is quota sampling
the population is split into groups and a certain number from each group is chosen in any order
can quota sampling be non-random
yes
what is opportunity sampling
a convenient sample is taken from any member of the population at any time
when should simple random sampling be used
when you want a random sample to avoid bias
when is simple random sampling useful
when you have a small population ir want a small sample
when should systematic sampling be used
when you want a random sample from a large population
when is systematic sampling useful
when there is a natural order
when should stratified sampling be used
when the population can be split into obvious groups of members
when is stratified sampling useful
when there are very different groups of members in a population
when should quota sampling be used
when a small sample is needed to be representative of the population structure
when is quota sampling useful
when a sampling frame is not available
when should opportunity sampling be used
when a sample is needed quickly
when is opportunity sampling useful
when a list of the population is not possible
what is 1 disadvantage of simple random sampling
cannot be used if it is not possible to number all the members of the population
what is 1 disadvantage of systematic sampling
cannot be used if it is not possible to number all the members of the population
what is 1 disadvantage of stratified sampling
cannot be used if the population cannot be split into seperate groups
what is 1 disadvantage of quota sampling
can introduce bias as some members of the population might choose not to be included in the sample
what is 1 disadvantage of opportunity sampling
unlikely to be representative if the population structure
