This document discusses different sampling techniques used in quantitative and qualitative research. It defines population and sample, and explains probability and non-probability sampling methods. Probability methods like simple random sampling, systematic sampling, stratified random sampling, and cluster sampling aim to give all members of the population an equal chance of being selected to reduce bias. Non-probability methods like convenience sampling, purposive sampling, quota sampling, consecutive sampling, and snowball sampling rely on the researcher's judgment and do not ensure representativeness. Choosing the appropriate sampling technique is important to validate research findings.
4. POPULATION
It means all members that meet a set of
specifications or a specified criterion. For
eg.Higher Secondary Students of Kerala
state.
5. SAMPLE
When only some elements are selected from a
population, we refer to that as a sample. It is
critical and an error at this stage will destroy
the integrity of the research. It should truly
represent the population.
7. In probability sampling every
member of the target population has
a known chance of being included in
the sample.
If the researcher is interested in generalizing the findings derived from
the sample to the general population, then probability sampling is far
more useful and precise.
9. SIMPLE RANDOM SAMPLING
It is the easiest form of probability sampling. Either a lottery method or
using a computer it can be done. Giving a number to each member of the
population and then selecting. Every member of the population has an equal
chance of being selected.
ADVANTAGES - Easy, fair and representative.
DISADVANTAGE - List of population should be complete and up to date.
May not be practical for a very large population.
10. SYSTEMATIC SAMPLING
It involves selection of every nth subject in the population to be in
the sample.
If you had a population of 500 students and you want to select 50
students as the sample, then we select every 10th member. We
can start a random starting point on the list. The starting point in
this case will be a number between 1 and 10. To select the starting
number random selection can be used.
11. STRATIFIED RANDOM SAMPLING
It involves the division of population into smaller sub-groups
known as strata. The strata are formed based on members'
shared attributes or characteristics such as type of family, family
income etc. It is also known as proportional random sampling or
quota random sampling. Population is divided into homogeneous
groups. Sample size from each strata should be proportional to the
population.
It makes sure that every category had a representation.
But dividing into strata and the basis of division may find difficult.
12. CLUSTER SAMPLING
The population is divided into different groups or clusters. Then the
required clusters are selected on a simple random or systematic
sampling method. Here all the subjects from the selected cluster will
be included in the sample.
For example you want to study parenting style patterns of standard 9 students of a
particular school. Population is 600 and want to select a sample of 50 and there are
12 divisions each comprising 50 students. Then you select a division on a random
basis and conduct study in that particular division.
13. Non probability
sampling
Individuals are selected based on non-
random criteria, and not every individual
has a chance of being included and so
has a higher risk of sampling bias.
15. CONVENIENCE SAMPLING
We select samples because they are conveniently available to the
researcher.,easy to recruit. the only criteria is whether the participants agree to
participate.
For example, you want to study the consumer behaviour at a supermarket. You
reach there and collect the required information from the consumers who are
present there at that time provided they are willing to participate.
It has a disadvantage of sampling error and lack of representativeness.
16. PURPOSIVE SAMPLING
In Purposive or judgemental sampling we choose only those people who are
deemed to be fit to participate in the research study. It is the discretion of the
researcher. It may not be statistically representative. The researchers get a lot of
information from the data. Time and cost effective.
It is prone to researchers bias.
For example if a researcher wants to study about the effective teaching methods
to teach poetry, he may approach the teachers whom the researcher see as
appropriate.
17. QUOTA SAMPLING
It is a nonprobabilistic version of stratified sampling. Population is first
segmented into mutually exclusive sub-groups.Then judgment is used to select
the subjects or units from each segment based on a specified proportion. it allows
the researchers to sample a subgroup that is of great interest to the study. But only
the selected traits of the population were taken into account in forming the
subgroups.
There is a nonrandom sample selection which differs it from stratified sampling.
18. CONSECUTIVE SAMPLING
Here every subject meeting the criteria of inclusion is selected
until the required sample size is achieved.
If a researcher is unable to obtain conclusive results with one sample,
he can depend on the second sample and so on for drawing conclusive
results.
19. SNOWBALL SAMPLING
It helps researchers to find a sample when they are difficult to locate, Once the
researchers find suitable subjects, he asks them for assistance to seek similar
subjects to form a considerably good size sample.
If you want to study about the living conditions of homeless people
in a certain town and the researcher finds it difficult to find the
sample, he finds one sample and ask him to refer another person.
This process continues till he reaches the required sample size.
20. The Difference
PROBABILITY SAMPLING
● sample selected at random.
● Everyone in the population
has an equal chance of
getting selected.
● Used to reduce sampling
bias
● Gets more accurate
sample.
NON PROBABILITY SAMPLING
● selection based on the subjective
judgment of the researcher.
● Not everyone has an equal
chance to participate
● does not consider sampling bias
● sample does not accurately
represent the population.
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Notes de l'éditeur
Sampling is a process used in statistical analysis in which a predetermined number of observations are taken from a larger population. The methodology used to sample from a larger population depends on the type of analysis being performed, but it may include simple random sampling or systematic sampling.
In random sampling, each member of the population has an equal and known chance of being selected.
non-probability sampling relies on the subjective judgement of the researcher.
Stratified - If there are 700 girls and 300 boys in a school, you may select 70 from girls and 30 from boys to ensure the representation.
Cluster - If there are 15 divisions for a standard in school select any 2 or 3 divisions in random taking all students from that division.
Systematic - Randomly select a starting number. Eg. every 5th member starting from number 3. In simple random we select every 5th starting from 1. (the starting number is selected in a random way like toss)
You want to study the parenting styles among primary school children of certain area in India.. Population may be thousand. But the native state of children are different. Mainly from 4 states. But the it is not proportionate. You think that the state from which they come from had an significant influence on parenting style. So you may divide the population according to their native place and select them proportionately for the sample..
researcher selects samples based on the subjective judgment of the researcher rather than random selection.