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Sampling Methods
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- 1Volunteer Sampling-A sample of participants that relies solely on volunteers to make up the sample.Also known as a self-selected sample.Advertise in a newspaper or on a notice board.Evaluation: STRENGTH-Gives access to a variety of participants(e.g. all the people who read a particular newspaper) which may make the sample more representative and less biased.
LIMITATION- Sample is biased in other ways because participants are more likely to be highly motivated and/or with extra time on their hands.They might be more highly motivated to be helpful, or more broke and needing the money offered for participation. This results in a volunteer bias. - 2Systematic Sampling- A sample obtained by selecting every nth person ( where n is any number). This can be a random sample of the first person is selected using a random method; you then select every nth person after that.Using a predetermined system to select participants, such as selecting every 6th,14th,20th (or whatever) person from a phone book. The numerical interval is applied consistently.Evaluation: STRENGTH- Unbiased as participants are selected using an objective system.
LIMITATION- Not truly unbiased/random unless you select a number using a random method and start with this person and then select the every nth person. - 3Random Sampling- A sample of participants produced using a random technique such as that every member of the target population being tested, has an equal chance of being selected.Lottery method, random number table,random number generator.Evaluation: STRENGTH- Unbiased, as all members of the target population have an equal chance of being selected.
LIMITATION- Need to have a list of members of the population and then contact all of those selected which may take some time. - 4Stratified Sampling- A sample of participants produced by identifying subgroups according to their frequency in the population. Participants are then selected randomly from subgroups. Subgroups( or strata) within a population are identified (e.g. boys and girls , or age groups). Participants are obtained from each of the strata in proportion to their occurrence in the population. Selection from the strata is done using a random technique.Evaluation: STRENGTH- Likely to be more representative than other methods because there's a proportional and randomly selected representation of subgroups.
LIMITATION- Very time consuming to identify subgroups, than randomly select participants and contact them. - 5Opportunity Sampling- A sample of participants produced by selecting people who are most easily available at the time of the study. Recruit those people who are most convenient or most available, for example people walking by you in the streets or students at school.Evaluation: STRENGTH- The easiest method because you just use the first suitable participants you can find, which it means it takes less time to locate your sample than if using one of the other techniques.
LIMITATION- Inevitably biased because the sample is drawn from a small part of the population, for example if you selected your sample from people walking around the centre of a town on a Monday morning to would be unlikely to include professional people( because they're at work) or people from rural areas
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- Karteikarten am Sampling Methods, erstellt von alexstoddard2626 am 18/12/2015.
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