Question

It is incumbent on the researcher to clearly define the target population. Sometimes, the entire population is small enough to be included in the study. In other instances, the population is too large for the researcher to attempt to survey all of its members. Therefore, a small, but carefully chosen sample is used to represent the population. The sample is the actual group targeted either directly or indirectly and reflects the characteristics of the population from which it is drawn.

Select at least two articles on sampling methodology used in public health research studies.

Based on the articles identified, create a document that includes the following:

·      A synopsis on the perspective of the sampling methodology used in your selected articles related to public health research studies.

·      Your opinion on whether the sampling method used in each of your chosen articles is appropriate for its target population. Justify your response.

·      An explanation of the potential advantages and disadvantages of the sampling plan used in your selected articles.

Please use references

Answer 1

Simple Random Sampling:
   It is the most straight forward probability sampling strategy..Here samples taken from population for a wide range of purposes..It has been started that the logic behind simple random samplings is that it removes bias from the selection procedure and should result in representative samples..Sample size need more than few hundred is required to apply simple randon samplings in a proper manner..In practical will be little difficult,it makes challenging when we work with large sample size to get a realistic sampling frame..Many researchers choose random sampling methods because representativeness of sample group and less room for researcher bias compared to non-random sampling techniques..
Application:
   Make list with all members of population and make mark with a specific number..use random number table or random number generator software..software option is best like research randomizer and stat Trek..In this researcher bias will be less..
There are two method of random sampling1.Lottery and random numbers..
Lottery: each number represent with mumber of population in a consequent manner,by writing numbers in seperate pieces of paper..Samples are to be taken randomly by choosing folded pieces of papers in a random manner..
Random number:
    It is an alternative method numbering of population members from 1 to N..then sample size of N has to be determined by selecting numbers randomly..
Advantages:
   -It has minimum amount of sampling bias compared to other sampling methods..
-It is easy to form the sample group..
-Research findings from the application of simple random sampling generalized due to representatives of this sampling technique and a little relevance of bias..
Disadvantages:
-It requires all potential respontents(sampling frame) and this is costly and time-consuming for large studies..
-for large sample size it can be major disadvantage
-This will not suitable for face-to-face interviews and studies covering a large geographycal area due to cost and time considerations..
Systematic sampling:
   It is a type of probability sampling method in which sample members from a large population are selected according to a random starting point and a fixed periodic interval..
   This sampling interval calculated by dividing the population in desired sample size..Since simple random sampling a population is inefficient and time-consuming,statisticians turn to other method like systematic sampling..It is a quick method,participant selection by fixed starting point has been identified and constant interval is selected..if you want to select a random group of 1000people from a population of 50,000,include potential participants.. every 50thperson on the list would be chosen as a participant,because 50,000/1000=50,if you want to select 20,70th person will be chosen followed by the 120th and soon..
Target population must be selected prior to selection..population can be identified by any number criteria may include age,gender,race,location,education anf profession
Advantages:
-It provide appropriate result..
-It is cost and time efficient
-suitable for any situation
-It is effectively suitable in collecting data from geographycally disperse case that means no need of any face-to-face contact..
Disadvantages:
-Systematic sampling can be applied only if the complete list of population is avialble..
-if there are periodic patterns in the dataset,the sample will be biased
-If study particiapants deduce the sampling interval,this can bias the population as non-participants will be different from study participants..
Reference:
http://research-methodology.net
http://www.cdc.gov/nchs/data/statnt/statnt21.pdf
http://www.healthknowledge.org.uk/