IntroductionTo getidea or information about a population we take a sample. sample – a part of the population that weexamine in order to gather information. It may be impossible to collect informationabout every member of the population. The information from a sample is oftenadequate and easier to obtain. The sampling design, the method chosen toselect the sample from the overall population, has important consequences. Poorsampling designs can yield misleading conclusions.
Literature ReviewSampling design is a method forobtaining a sample from a certain population.Data can be collected by twomethods 1- census 2- sampling.Sampling reduces the studypopulation to a reasonable size that reduces the expenses.Sampling also prevent time consumingresearch.
It take too much time to cover the whole population so within areasonable time period we can complete our research. A sampling method is biased ifit systematically favors certain outcomes so sample should be valid and it canbe valid in two ways first one is accuracy and second is precision. The sample design plans includes informationabout sampling frames and their coverage, providing descriptions of thenational sample designs that included stages of sampling, probabilities ofselection, sampling units and sample sizes. The sample selection plans includesdetailed information about the processes for sample selection at each stage ofsampling. 1 General types of sampling1.
Probability sampling2. Non Probability samplingProbability Sampling The sample is the proportion of thepopulation and such sample is selected from a population by means of systematicway in which every element of population has a chance of being selected insample. Probability sampling involves convenience sampling, purposive sampling,But this method is too muchexpensive, time consuming and complex.Non probability SamplingThe sample is not a proportion ofpopulation and there is no system in selecting the sample.
We can’t use the mathematics of probability to analyze theresults. Non probability sampling includes pure random sampling, systematicsampling, stratified sampling and cluster sampling. 2 3 Errors in sampling1. SamplingErrors2.
NonSampling ErrorsSampling Errors· Faultysample design · Smallsize of sampleNon Sampling Error· Coverage Error· Observational Error· Processing Error 2 4ConclusionBy using a proper and suitablesample design we can do a better research in very less time and cost with timeefficiency. By this we can get detailed and practical information about apopulation. Once you know about your population, sampling frame, samplingmethod and sample size you can use all that information to choose your sample.References1. Europeancommunities (2008). Surveysampling reference guidelines – Introduction to sample design and estimationtechniques Luxembourg: Office for OfficialPublications of the European Communities2. Cochran,W.G.
(1977). Sampling Techniques, 3rd ed. New York: John Wiley .3. HansenM.H., Hurvitz W.N.
& Madow W.G. (1953). Sample survey methods and theory. New York: John Wiley & Sons.
4. LesslerJ. & Kalsbeek W.
(eds.). 1992. Nonsampling Error in Surveys.
NewYork: JohnWiley& Sons.