statistics Flashcards
population
the population is everyone or everything you are interested in
census
if you collect data from the whole population its called a census
sample
if you collect data from part of the population its called a sample
sampling unit
the population broken down into sectors
sampling frame
how you can get a list of the population
simple random sampling method
everyone has equal chance of getting picked
this can be done many ways for example giving everyone in you population a number and then using a random number generator to randomly pick people
pros of random sampling method
-no bias
-efficient and chap if population is small
-every person has equal chance
cons of random sampling methods
- could be not representative of the whole group
-not suitable for a large sample
-need a full sampling frame
systematic sampling method
randomly pick a number one then pick everyone after in a set interval
pros to systematic sampling
-simple and quick
-suitable for a large population
cons to systematic sampling
-need sampling frame
- bias can happen if sampling frame not random
stratified sampling method
split population into strata’s (groups) to insure each group is proportionally represented as the sample is split in proportional to the population
stratified sampling pros
-sample reflects the proportion structure
-proportionally representative of al the groups in the population
stratified sampling cons
-have to organise population into strata’s
-could suffer from all the con s of the other two as they are often used within this method
quota sampling method
picking people that match your criteria only and selecting them using convenience sampling