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Thursday, 29 August 2019

Proportionate and stratified proportionate sampling
Proportionate Sampling 
Proportionate sampling is a sampling strategy (a method for gathering participants for a study) used when the population is composed of several subgroups that are vastly different in number. The number of participants from each subgroup is determined by their number relative to the entire population(‘Proportionate stratified sampling—Oxford Reference’, n.d.).


For example. imagine you want to create a council of 20 employees that will meet and recommend possible changes to the employee handbook(Hayes, n.d.). Let's say 40% of your employees are in Sales and Marketing, 30% in Customer Service, 20% of your employees are in IT, and 10% in Finance. You will randomly select 8 people from Sales and Marketing, 6 from Customer Service, 4 from IT, and 2 from Finance. As you can see, each number you pick is proportionate to the overall percentage of people in each category (e.g., 40
Stratified sampling 
On: Stratified sampling is a type of sampling method in which the total population is divided into smaller groups or strata (‘Stratified Sampling: Definition’, n.d.)
to complete the sampling process The strata is formed based on some common characteristics in the population data. After dividing the population into strata, the researcher randomly selects the sample proportionally.  Description: Stratified sampling is a common sampling technique used by researchers when trying to draw conclusions from different sub-groups or strata. The strata or sub-groups should be different and the data should not overlap. While using stratified sampling, the researcher should use simple probability sampling. The population is divided into various subgroups such as age, gender, nationality, job profile, educational level etc. Stratified sampling is used when the researcher wants to understand the existing relationship between two groups.


The researcher can represent even the smallest sub-group in the population. There are two types of stratified sampling – one is proportionate stratified random sampling and another is disproportionate stratified random sampling. In the proportionate random sampling, each stratum would have the same sampling fraction. For example, you have three sub-groups with a population size of 150, 200, 250 subjects in each subgroup respectively. Now, to make it proportionate, the researcher uses lone specific fraction or a percentage to be applied on its subgroups of population. The sample for first group would be 150*0.5= 75, 200*0.5=100 and 250*0.5= 125. Here the constant factor is the proportion ration for each population subset. 
The only difference is the sampling fraction in the disproportionate stratified sampling technique. The researcher could use different fractions for various subgroups depending on the type of research or conclusion he wants to derive from the population(Crossman, n.d.). The only disadvantage to that is the fact that if the researcher lays too much emphasis on one subgroup, the result could be skewed



Table 1
Advantages and disadvantages of various technique


Technique

Advantages

Disadvantages
Simple random

Highly representative

Un economical to achieve  
Stratified random

It ensure that specific group or represented

More complex, require more effort 
Cluster

Possible to select randomly when no single list of population numbers existed

It must be equalent and some natural ones are not  for essential characteristics


 

                     Figure1.Stratified random sample


Reference
Crossman, A. (n.d.). Understanding Stratified Samples and How to Make Them. Retrieved 20 August 2019, from ThoughtCo website: https://www.thoughtco.com/stratified-sampling-3026731
Hayes, A. (n.d.). Reading Into Stratified Random Sampling. Retrieved 20 August 2019, from Investopedia website: https://www.investopedia.com/terms/stratified_r 
Crossman, A. (n.d.). Understanding Stratified Samples and How to Make Them. Retrieved 20 August 2019, from ThoughtCo website: https://www.thoughtco.com/stratified-sampling-3026731
Hayes, A. (n.d.). Reading Into Stratified Random Sampling. Retrieved 20 August 2019, from Investopedia website: https://www.investopedia.com/terms/stratified_random_sampling.asp
Proportionate stratified sampling—Oxford Reference. (n.d.). https://doi.org/10.1093/oi/authority.20110803100349910
andom_sampling.asp
Proportionate stratified sampling—Oxford Reference. (n.d.). https://doi.org/10.1093/oi/authority.20110803100349910


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