Quota sampling, a nonprobability sampling method, is a viable approach to serve the needs of the researcher. Although there are several different purposeful sampling strategies, criterion sampling appears. Application of quota sampling ensures that sample group represents certain characteristics of the population chosen by the researcher. Characteristics, benefits, crucial issues draw backs, and examples of each sampling type are provided separately. For example, you could divide a population by the state they live in, income or education level, or sex. If the population size is 500, the researcher can pick a sample of 50 elements. Quota sampling emerges as an attractive choice when you are pressed for time, because primary data collection can be done in shorter time.
As opposed to random sampling, quota sampling requires that representative individuals are chosen out of a specific subgroup. A practical guide to sampling national audit office. For example, if you are sampling 1,000 people you might choose a quota sample of 100. Suppose that you are required to conduct a survey regarding the choice of colors by females for a fashion designer. Many higher education institutes use quota sampling to diversify their batches. Stratified sampling without callbacks may not, in practice, be much different from quota sampling. Mar 30, 2018 in quota sampling, the researcher aims to represent the major characteristics of the population by sampling a proportional amount of each. Purposive sampling is used in cases where the specialty of an authority can select a more.
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. 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. If we were to examine the differences in male and female students. The most notable is the bias of non response when for some reason some units have no chance of appearing in the sample. The researcher here is ease of access to his sample population by using quota. How much scope is there for collecting a good quality quota sample. This method is most often used in online research conducted through panels. A lucky draw for six hampers in a ums family day e.
Next, the researcher must choose their sample size. Sampling bias is usually the result of a poor sampling plan. For example, you can select a total sample of 500 students from a population of 50,000 students. Example of quota sampling suppose that you are required to conduct a survey regarding the choice of colors by females for a fashion designer. The three will be selected by simple random sampling. The focus here is on specific sampling issues of the swts comprising sample design, implementation and measuring sampling errors. Yamane, p3 examples of nonprobability sampling used extensively in 1920s and 1930s are the judgment sample, quota sample, and the mail questionnaire. One of the problems with quota samples is the difficulty to include some respondents rather than others.
This sampling method is used so that the proportion of samples for each category such as female or under 25 years old will have the same proportion assumed to exist in. Quota sampling preplan number of subjects in specified categories e. For example, a researcher might ask for a sample of 100 females, or 100 individuals between the ages of 2030. In proportional quota sampling you want to represent the major characteristics of the population by sampling a proportional amount of each. Here are three simple examples of nonprobability sampling to understand the subject better. The explanations below are meant to help you understand the reasons for using each method.
Different target audiences provide various challenges for finding the correct quota numbers. A sampling method of gathering representative data from a group. Ch7 sampling techniques university of central arkansas. You are doing research on working conditions at company x. Quota sampling method is a nonprobability sampling and it can be defined as a sampling method of gathering representative data from a group. For example, if you wanted to obtain a proportional quota sample of 100 people based on gender, you would need to start with an understanding of the manwoman ratio in the larger population. For example, a quota sample might have interviewerassigned quotas for age by gender by employment status categories. 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. 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. To get an accurate view of the data, you will need to collect data from different sections of the population of different age groups. Quota sampling is a type of nonprobability sampling technique.
In quota sampling, interviewer selects first available subject who meets criteria. Quota sampling methodology aims to create a sample where the groups e. For instance, if you know the population has 40% women and 60% men, and that you want a total sample size of 100, you will continue sampling until you get those percentages and then you will stop. Learn the pros and cons of quota sampling in this article. Quota sampling relies on the researchers judgement in choosing the right subgroups and giving them the right weightages. Nonprobability sampling research methods knowledge base. This random element is its greatest spatial sampling spatial sampling is an area of survey sampling associated with sampling in. If the list is not available, we need to conduct a. Here, the researcher chooses sample members at will.
For instance, a representative sample is often considered one of the most important criteria when evaluating the quality of a sampling survey, and a sample is considered to be representative if the sample structure is the same or close to the population structure. The target population in a sampling survey can often be divided into several subpopulations based on certain characteristics of the population units. The interviewer has been given quotas to fill from specified subgroups of the population, e. 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. There are lot of techniques which help us to gather sample depending upon the need and situation. Given that all the quotas are correctly and honestly filled. At last, our series of posts on sampling, has reached the allstar of nonrandom sampling.
It can easily be administered and helps in quick comparison. Quota sampling characterizes the population based on certain desired features and assigns a quota to each subset of the sample population. Moreover, the variance of the sample mean not only depends on the sample size and sampling fraction but also on the population variance. It involves a twostep process where two variables can be used to filter information from the population. These are hypothetical examples of what is the crucial problem of quota sampling. For instance, in the previous example, the interviewer may quickly find ten females, and five males in the age group 1521, but it may take a lot. In quota sampling, the researcher aims to represent the major characteristics of the population by sampling a proportional amount of each.
Pros of quota sampling quota sampling is particularly useful when. This technique is known as one of the easiest, cheapest and least timeconsuming types of sampling methods. Probability sampling, quota sampling, representativeness, response rate, social capital introduction 1. Sampling involves the selection of a portion of the population being studied. 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.
Quota sampling is very arbitrary and likely to figure in municipal surveys. It is this second step which makes the technique one of nonprobability sampling. The sampling frame is the list of ultimate sampling entities, which may be people, households, organizations, or other units of analysis. The application of quota sampling can be costeffective. Researchers can send the survey to students belonging to a particular school, college, or university, and they would act as a sample in this situation. Purposeful sampling for qualitative data collection and. Quota sampling as an alternative to probability sampling. Sampling theory chapter 9 cluster sampling shalabh, iit kanpur page 5 comparison with srs.
In quota sampling, a researcher first identifies relevant categories. Please note that random sample does not mean arbitrary sample. Digest successfully predicted the presidential elections in 1920, 1924,1928, 1932 but. If an equivalent sample of nm units were to be selected from the population of nm units by srswor, the variance of the mean per element would be 2 2 22 11 2 2 1 where and. A manual for selecting sampling techniques in research. Jan 01, 2017 created using powtoon free sign up at create animated videos and animated presentations for free. Advantages a it is an improvement over the judgement sampling. This type of sampling technique is also known as purposive sampling and authoritative sampling.
In quota sampling, the selection of the sample is nonrandom. In that case, we need a sampling list of baltimore hhs. Each individual is chosen randomly and each member of the population has an equal chance of being included in the sample. For example, a quota sample of men and women to assess prevalence of. If anything goes wrong with your sample then it will be directly reflected in the final result. Quota sampling with proportional quota sampling, the aim is to end up with a sample where the strata groups being studied e.
Quota sampling falls under the category of nonprobability sampling. Proportionate sample quota sampling is a method of nonprobability samplingwhen the samples are selected based on the probability. Proportional quota sampling goal is to create a sample in which the groups that are being studied are proportional to their representation in the population being studied example. Sample for each category selected randomly from the. Purposive sampling is a nonprobability sampling method and it occurs when elements selected for the sample are chosen by the judgment of the researcher. History of sampling contd dates back to 1920 and started by literary digest, a news magazine published in the u. The research sample, using simple random sampling in which all teachers had an equal chance of being included in the sample taherdoost, 2016, was teachers of english in schools of primary and secondary education from the prefectures of ioannina and. The research sample, using simple random sampling in which all teachers had an equal chance of being included in the sample taherdoost, 2016, was teachers of english in schools of primary and secondary education from the prefectures of ioannina and thesprotia, in the region of epirus, in greece. Uncontrolled quota sampling does not impose any restrictions on the researchers choice of samples.
There are a large number of tasks behind quota sampling. As data collectors, you will not be responsible for selecting the sampling method. The auditor should also take care to check the quality of the information from which the sample is to be drawn. Judgmental sampling is a nonprobability sampling technique where the researcher selects units to be sampled based on their knowledge and professional judgment. Purposeful sampling is widely used in qualitative research for the identification and selection of informationrich cases related to the phenomenon of interest. For example, if the researcher selects 1012 individuals from the waiting area without any structure, it is not a random sample. Quota sampling means to take a very tailored sample thats in proportion to some characteristic or trait of a population. For example interviewers might be tempted to interview those who look most helpful. In the third step of quota sampling, the researcher should select the sample size while maintaining the proportion evaluated in the previous step. Sampling bias is a tendency to favour the selection of units that have paticular characteristics. In quota sampling, you select people nonrandomly according to some fixed quota. For these reasons, we do not think quota sampling should be taken as an acceptable alternative to probability sampling. In taking a sample of villages from a big state, it is more administratively convenient to consider the districts as strata so that the administrative set up at district level may be used for this purpose.
Quota sampling methods are sometimes criticized because the sampled results can be unreliable at times. In addition to this, the researcher must make sure that the composition of the final sample to be used in the study meets the. Quota sampling applied in research nonprobability sampling. Then judgment is used to select the subjects or units from each segment based on a specified proportion. Jun 25, 2015 quota sampling means to take a very tailored sample thats in proportion to some characteristic or trait of a population. When we take the samples from a group of items with specific traits or specific characteristics in proportion to their size in the population, this is called quota sampling. 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. This makes quota sampling popular in undergraduate and masters level dissertations where there is a need to divide the population. Quota sampling is a sampling methodology wherein data is collected from a homogeneous group. Oct 25, 2009 quota sampling in quota sampling the selection of the sample is made by the interviewer, who has been given quotas to fill from specified subgroups of the population. Example if we are interested in studying population of 40 percent of females and 60 percent of males. As described later in this chapter, such selection is sampling without replacement.
In the above example, proportional quota sampling was used. Quota sampling is not dependent on the presence of the sampling frames. An example of convenience sampling would be using student volunteers known to the researcher. Highly controlled quota sampling uses probability sampling down to the last block or telephone exchange. In nonpraobability sampling, often, the surveyor selects a sample according to his convenience, or generality in nature. Choosing a quota sample can be broken down into three steps. 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. Your sampling frame is the companys hr database which lists the names and contact details of every employee. Proportional quota sampling was used to recruit respondents, with quotas based on sex, age, working status, residential location, housing tenure, and ethnicity. Quota sampling is a nonprobability sampling technique in which.
The quota sampling is yet another nonprobability sampling method wherein the population is divided into a mutually exclusive, subgroups from which the sample items are selected on the basis of a given proportion. A random sample is a probability sample where every individual has an equal and independent probability of being selected in the sample. Caveats sampling can provide a valid, defensible methodology but it is important to match the type of sample needed to the type of analysis required. When properly conducted, it can produce good estimates of the target population. Foot measurement study of the population of taiwan. Researchers often believe that they can obtain a representative sample by using a sound judgment, which will. 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. Some common variables used to categorize population include gender, age, location, education level, and so forth. All of them use the facetoface interview as the survey procedure. The manual for sampling techniques used in social sciences is an effort to describe various types of sampling methodologies that are used in researches of social sciences in an easy and understandable way. For example interviewers might be tempted to interview those who look. This module also explores and provides detailed guidelines for sampling frameworks when they are readily available from other. For example, an interviewer may be told to sample 50 females between the age of 45 and 60. It is one of the most important factors which determines the accuracy of your researchsurvey result.
The problem is that these samples may be biased because not everyone gets a chance of selection. The population is divided into groups also called strata and samples are taken from each group to meet a quota. Regardless of the population specifics, however, the key to proper quota sampling is to make certain your quota numbers reflect the percentages of traits that are present in your surveys population. Quota sampling is a method of nonprobability sampling when the samples are selected based on the probability proportionate to the distribution of a variable in the population. 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.
Failed in 1936 the literary digest poll in 1936 used a sample of 10 million, drawn from government lists of automobile and telephone. This article explains a what quota sampling is, b how to create a quota sample, and. In a school population of students, 40% are male and 60% are female. A researcher wants to survey individuals about what smartphone brand they prefer to use. Thus in our example, the randomly selected numbers are 2, 5 and 8 used to randomly sample the subjects in figure 31. Gsr quota sampling guidance uk statistics authority.
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