Sampling Flashcards
How to take a random sample
Assign each person with a number (001-100)
use random number generator to select number and write them down
reject numbers outside sample number e.g 000
ignore repeats
continue until number of sample size is collected e.g 10
then use number to select corresponding individuals
Stratified random sample
calculate cumber of individuals from each strata have been selected in sample ( if 20% of population is in strata sample of 2- would need 4 from that strata)
use random sampling method to select people in strata
systematic sampling
divide population size by sample size to calculate interval
assign ppl in population with number -same as random sampling
number selected and every number one interval on is selected
corresponding people are then selected
Quota sampling
stratified sample where samples for each strata are chosen for convenience
sampler picks people in strata
cluster sampling
population divided into clusters
often chosen for geographical convinience
uses random chosen clusters
people in small clusters are more likely to be picked than those in large clusters
advantage and disadvantage of cluster sampling
+ easy to administer
- ppl in cluster may have same views
advantage and disadvantage of random sampling
+ simple and easy to use where small populations involved.
+ sample is representative
- more time consuming and costly to carry out
- doesn’t ensure all strata are fairly represented
advantage and disadvantage of systematic sampling
+easier and quicker and cheap
+ can give useful results if population doesn’t follow pattern
- method may interact with a hidden pattern leading to bias
advantage and disadvantage of stratified sampling
+ensures all strata are fairly represented
+sample is representative as randomly chosen
-need prior knowledge
- more complicated to administer
advantage and disadvantage of cluster sampling
+ less costly in terms of travelling, time and money
+ contains elements of randomness
- subjects within a cluster may have similar views
