Sampling & Data Collection Flashcards
(37 cards)
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 3 disadvantages of a census
- time-consuming and expensive
- cannot be used when the testing process destroys the item
- hard to process large quantity of data
give 3 advantages of sampling
- less time consuming and expensive
- fewer people have to respond
- less data to process than in a census
give 1 disadvantages of sampling
- data may not be as accurate
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 are the advantages and disadvantages of simple random sampling
Pros:
- prevents bias
- easy and cheap to do for a small population or a small sample
- each sampling unit has an equal chance of selection
Cons:
- very time-consuming and expensive when the population size od sample size is very big
- a sampling frame is needed
what are the advantages and disadvantages of systematic sampling
Pros:
- simple and quick to use
- suitable for large samples and large populations
Cons:
- a sampling frame is needed
- it can introduce bias if the sampling frame is not random
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 are the advantages and disadvantages of stratified sampling
Pros:
- sample accuracy reflects the population structure
- guarantees proportional representation of groups within a population
Cons:
- population must be clearly classified into distinct strata
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
what are the advantages and disadvantages of quota sampling
Pros:
- allows a small sample to still be representative of the population
- no sampling frame required
- quick, easy and cheap
- allows for easy comparison between different groups within a population
Cons:
- non-random sampling introduces bias
- the population must be divided into groups, which can be expensive and inaccurate
