To create a quota sample, knowledge about the population and the objective should be well understood so that the researcher can choose the relevant stratification. The three will be selected by simple random sampling. Quota sampling is a non random sampling technique in which participants are chosen. While this sampling technique might be very representative of the quotadefining characteristics, other important characteristics may be disproportionately. Purposive sampling is an informant selection tool widely used in ethnobotany table 1. It saves time and money both at the same time by giving us important information about how many samples of each group we need to collect. Sampling may be done either a probability or a nonprobability basis. Quota sampling as an alternative to probability sampling. In probability sampling each element in the population has a known nonzero chance of being selected through the use of a random selection procedure such as simple random sampling. It can easily be administered and helps in quick comparison. According to showkat and parveen 2017, the snowball sampling method is a nonprobability sampling technique, which is also known as referral sampling, and as stated by alvi 2016, it is.
There are lot of techniques which help us to gather sample depending upon the need and situation. Then judgment is used to select the subjects or units from each segment based on a specified proportion. In this context, this guidance on quota sampling is both necessary and timely. Purposeful sampling for qualitative data collection and. A manual for selecting sampling techniques in research. Comparision of snowball sampling and sequential sampling. Subsequently, sampling units are selected to complete each quota. Proportional quota sampling the proportional in the. Note that the two methods are not mutually exclusive, and may be used for different purposes at different. Comparison of stratified sampling with quota sampling. It involves a twostep process where two variables can be used to filter information from the population. Quota sampling a guide government statistical service. Therefore, we may choose to study a sample of the population.
It is also common in a sampling survey situation that investigators might require certain propositions or numbers for each type of sampling unit included in the sample for various reasons. This technique is known as one of the easiest, cheapest and least timeconsuming types of sampling methods. In quota sampling, a researcher first identifies relevant categories. It also presents different scenarios and methods of dealing. This type of sampling is also known as nonrandom sampling. In simple terms, in multistage sampling large clusters of population are divided into smaller clusters in several stages in order to. Quota sampling is a type of nonprobability sampling technique. So why should we be concerned with simple random sampling. Jul 26, 2018 this technique is more reliant on the researchers ability to select elements for a sample. This makes quota sampling popular in undergraduate and masters level dissertations where there is a need to divide the population. When properly conducted, it can produce good estimates of the target population. For these reasons, we do not think quota sampling should be taken as an acceptable alternative to probability sampling.
Some common sample designs described in the literature include purposive sampling, random sampling, and quota sampling cochran 1963, rao 1985, sudman 1976. Population sampling techniques when we are interested in studying a population, it is often not feasible or possible to study the entire population, particularly if it is large or hard to access. A quota sample can also be achieved on a low budget because of this. Also, since quota sampling does not need a sampling frame or spelling techniques, it is easier and quicker to perform. In quota sampling, you select people nonrandomly according to some fixed quota. Used when a sampling frame not available or too expensive, and b cost of reaching an individual element is too high. If the participants in quota sampling are assigned equal probability of being included in the sample, quota sampling will be equivalent to stratified sampling, which is a probability sampling method, and the results of both methods should be the same or very close. Quota sampling is a nonprobability sampling technique wherein the assembled sample has the same proportions of individuals as the entire population with respect to known characteristics, traits or focused phenomenon. All of them use the facetoface interview as the survey procedure. Mar 30, 2018 quota sampling is advantageous in that it can be fairly quick and easy to assemble a quota sample locally, which means it has the benefit of timesaving within the research process. The sampling frame is the list of ultimate sampling entities, which may be people, households, organizations, or other units of analysis.
Quota sampling, a nonprobability sampling method, is a viable approach to serve the needs of the researcher. How to choose a quota sample choosing a quota sample can be broken down into three steps. Area probability sampling techniques are used to select primary sampling units and segments. Munich personal repec archive a manual for selecting sampling techniques in research alvi, mohsin university of karachi, iqra university 23 march 2016 online at mpra paper no. Quota sampling is a sampling methodology wherein data is collected from a homogeneous group.
In simple terms, in multistage sampling large clusters of population are divided into smaller clusters in several stages in order to make primary data collection more manageable. Many higher education institutes use quota sampling to diversify their batches. The results suggest that the survey topic influences who responded and that the response rate was associated with the sample means as well. As part of casros great series of webinars, john bremer of the npd group discussed elements of nonprobability seminar. This makes quota sampling popular in undergraduate and masters level. Gsr quota sampling guidance uk statistics authority. Quota sampling falls under the category of nonprobability sampling.
Researchers choose these individuals according to specific traits or qualities. In proportional quota sampling you want to represent the major characteristics of the population by sampling a proportional amount of each. There are a large number of tasks behind quota sampling. Purposeful sampling is a technique widely used in qualitative research for the identification and selection of informationrich cases for the most effective use of limited resources patton, 2002. A manual for selecting sampling techniques in research munich. Best practice for quota sampling when it should be used o when there are compelling reasons not to use probability sampling o when a broad brush answer or preliminary information prior to probability sampling is needed how it should be used o with carefully designed quotas using existing data o with properly trained interviewers. Some common variables used to categorize population include gender, age, location, education level, and so forth. Quota sampling is defined as a nonprobability sampling method in which researchers create a sample involving individuals that represent a population. Quota sampling is widely adopted these days because of its many benefits. As the survey was administered online, a quota sampling technique was chosen. The focus here is on specific sampling issues of the swts comprising sample design, implementation and measuring sampling errors. Quota sampling relies on the researchers judgement in choosing the right subgroups and giving them the right weightages. It is this second step which makes the technique one of nonprobability sampling.
Sampling techniques in this lecture, our focus only on sampling to really understand and mastery various techniques of sampling impossible to be achieved in just a lecture or in one semester course it is through a lifetime practice as a scientist but it is possible if just only one sampling technique. This module also explores and provides detailed guidelines for sampling frameworks when they are readily available from other surveys. This is an important research design decision, and one which will depend on such factors as whether the theory behind the research is positivist or idealist, whether qualitative or quantitative methods are used etc. Pdf researchers assessed the psychological and behavioural reactions of. Advantages a it is an improvement over the judgement sampling. Nonprobability sampling focuses on sampling techniques that are based on the judgement of the researcher see our article nonprobability sampling to learn more about nonprobability sampling. Besides touching on probability sampling, sample matching, and calibration, he presented an excellent taxonomy of the different types of nonprobability sampling. Instead, you simply want to have enough to assure that you will be able to talk about even small. Nonproportional quota sampling is a bit less restrictive. Here, we describe, discuss, and evaluate four prominent sampling strategies in developmental science.
The purposive sampling technique, also called judgment sampling, is the deliberate choice of an informant due to the qualities the informant possesses. The main reason is to learn the theory of sampling. Sampling involves the selection of a portion of the population being studied. The explanations below are meant to help you understand the reasons for using each method. Purposive sampling as a tool for informant selection. As data collectors, you will not be responsible for selecting the sampling method. Insights from an overview of the methods literature stephen j. Quota sampling is a nonprobability sampling technique in which researchers look for a specific characteristic in their respondents, and then take a tailored sample that is in proportion to a population of interest. Insights from an overview of the methods literature abstract the methods literature regarding sampling in qualitative research is characterized by important inconsistencies and ambiguities, which can be problematic for students and researchers seeking a clear and coherent understanding. Quota sampling applied in research nonprobability sampling. Application of quota sampling ensures that sample group represents certain characteristics of the population chosen by the researcher. Probability sampling means that every member of the population has a chance of being selected. In the section which sampling technique to use in your research, it has been tried to describe. Unlike probability sampling techniques, especially stratified random sampling, quota sampling is much quicker and easier to carry out because it does not require a sampling frame and the strict use of random sampling techniques i.
The extra information speeds up the sampling process. Using a quota sampling technique, as described earlier, the interviewer selects a sample of. Simple random sampling, systematic sampling, stratified sampling fall into the category of simple sampling techniques. Quota sampling is a nonprobability sampling technique in which researchers look for a specific characteristic in their respondents, and then take. Although sampling has farreaching implications, too little attention is paid to sampling. Introduction since the earliest applications of quota sampling in the early twentieth century, there has been a wealth of references to its unsuitability for some purposes, such as to obtain populationrepresentative samples 16. These features make quota sampling a useful tactic for field research. The hypothesis to be tested is that it is possible to achieve the same degree of representativeness using a combination of random route sampling and quota sam. Quota sampling is very arbitrary and likely to figure in municipal surveys. In addition to this, the researcher must make sure that the composition of the final sample to be used in the study meets the. Outcome of sampling might be biased and makes difficult for all the elements of population to be part of the sample equally.
A disadvantage is that it is difficult to see potential sampling errors. The qualitative report 2015 volume 20, number 11, article 4, 17721789. Learn the pros and cons of quota sampling in this article. The primary goal of sampling is to get a representative sample, or a small collection of units. If anything goes wrong with your sample then it will be directly reflected in the final result. Cluster sample a sampling method in which each unit selected is a group of persons all persons in a city block, a family, etc. Quota sampling has some similarities to stratified sampling. The interviewer has been given quotas to fill from specified subgroups of the population, e. Purposive sampling in this technique, sampling units are selected according to the purpose. The words that are used as synonyms to one another are mentioned. Nonrandom sampling is widely used as a case selection method in qualitative research, or for quantitative studies of an exploratory nature where random sampling is too costly, or where it is the only feasible alternative.
Rapid surveys are no exception, since they too use a more complex sampling scheme. Quota sampling methodology aims to create a sample where the groups e. A sampling frame is a list of the actual cases from which sample will be drawn. The random sampling can also be of different types. Nonprobability sampling research methods knowledge base. One of the advantages of quota sampling is it helps create an accurate sample of the population when a probability sample cannot be obtained. In this method, you specify the minimum number of sampled units you want in each category. Quota sampling in quota sampling, the population is first segmented into mutually exclusive subgroups, just as in stratified sampling.
Ch7 sampling techniques university of central arkansas. Quota sampling methods are sometimes criticized because the sampled results can be unreliable at times. Sampling methods, random sampling, multistage cluster sampling, random route method, quota sampling 1. This article explains a what quota sampling is, b how to create a quota sample, and. A nonprobability sampling method, where respondents have an unknown probability of being selected. A manual for selecting sampling techniques in research 5 of various types of probability sampling technique. Contacting members of the sample stratified random sampling convenience sampling quota sampling thinking critically about. The survey is designed to interview quotas of different types of respondent. The non proportional quota sampling is a technique with small restriction of minimum of sample number of unit from each category. If you want to produce results that are representative of the whole population, you need to use a probability sampling technique.
The underlying reasoning behind quota sampling is that if the sample effectively represents the population characteristics that have a greater correlation with the study variable, this will also be correctly represented. Multistage sampling this sample is more comprehensive and representative of the population. Sampling techniques introduction to sampling distinguishing between a sample and a population simple random sampling step 1. The target population in a sampling survey can often be divided into several subpopulations based on certain characteristics of the population units. Quota sampling is a nonrandom and nonprobability sampling technique that is based on a previously decided number of respondents and subdivides the population in different strata sedgwick, 2012. They decide and create quotas so that the market research samples can be useful in collecting data. It is one of the most important factors which determines the accuracy of your researchsurvey result. Appendix iii is presenting a brief summary of various types of nonprobability sampling technique. Nonprobability sampling is a sampling procedure that will not bid a basis for any opinion of probability that elements in the universe will have a chance to be included in the study sample. Division of research techniques, london school of economics and political science. Used when a sampling frame not available or too expensive, and. What are the advantages and disadvantages of quota sampling. Multistage sampling also known as multistage cluster sampling is a more complex form of cluster sampling which contains two or more stages in sample selection. However, the use of the method is not adequately explained in most studies.