quota sampling
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A PRESENTATION ON “QUOTA SAMPLING”
Presented By: (ARYAN’S) Abishek Kumar Ajit Kumar Gaganjit singh Praveen Kumar Sumanto Sharan Swapnil Adahalli
SAMPLING Sampling may be defined as the selection of some part of an aggregate or totality on the basis of which a judgement or inference about the aggregate or totality is made.
It is the process of obtaining information about an entire population by examining only a part of it.
The process of selecting sample from the population is called sampling.
WHY SAMPLE ?
Saves moneySaves timeA sample can be more accurate; it has fewer “nonsampling” errors than a census.
TYPES OF SAMPLING
PROBABILITY SAMPLING
Simple random sampling Systematic random sampling Stratified sampling Cluster sampling Multi-stage sampling
NON-PROBABILITY SAMPLING
Deliberate sampling Quota sampling Sequential sampling Snowball sampling Panel sampling Shopping mall sampling
QUOTA SAMPLING
In quota sampling the selection of the sample is made by the interviewer, who has been given quotas to fill from specified sub-groups of the population.
For example, an interviewer may be told to sample 50 females between the age of 45 and 60.
QUOTA SAMPLING
In quota sampling the selection of the sample is non-random.
For example interviewers might be tempted to interview those who look most helpful. The problem is that these samples may be biased because not everyone gets a chance of selection. This random element is its greatest weakness and quota versus probability has been a matter of controversy for many years
CONT…..
Pre-plan number of subjects in specified categories (e.g. 100 men, 100 women) In uncontrolled quota sampling, the subjects chosen for those categories are a convenience sample, selected any way the interviewer chooses
In controlled quota sampling, restrictions are imposed to limit interviewer’s choice No call-backs or other features to eliminate convenience factors in sample selection
QUOTA SAMPLING…..
Quota Sampling Most commonly used non-probability method Select a sample on specified criteria (usually to make similar to target population)
Pick people to fill quota on characteristics especially important to research goals
Example: Studying political issues, set quota on party identification
Sample of 200 Registered Republicans 50% Sampled Republicans 100 Registered Democrats 40% SampledDemocrats 80 Registered Independents 10% SampledIndependents 20
Using quotas for several criteria
Race/Ethnicity Black White Latino/a Asian Gender Gender Gender Gender
Political M F M F M F M F Affiliation Democratic Republican Independent
Quick and cheap to organise
Advantages
Not as representative of the population as a whole as other sampling methods Because the sample is non-random it is impossible to assess the possible sampling error
Disadvantages
Quota Vs Stratified Sampling
QUOTA SAMPLING STRATIFIED SAMPLING
In Quota Sampling, interviewer selects first available subject who
meets criteria: is a convenience sample.
In Stratified Sampling, selection of subject is
random. Call-backs are used to get that particular
subject
Highly controlled quota sampling uses probability sampling down to the last
block or telephone exchange
Stratified sampling without call-backs may
not, in practice, be much different from quota
sampling.
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