• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# The Advantages and Disadvantages of Quota Sampling Compared to Random Sampling

Extracts from this document...

Introduction

Introduction

Quota sampling is a non-probability sampling method, compared to random sampling methods, which are known as probability sampling methods. Examples of probability methods are stratifying sampling, cluster sampling, systematic sampling and simple random sampling. When a sample needs to be taken from a population, the issue of which type of sampling method to use arises; probability or non-probability. Since we are looking at specifically quota sampling, we need to define it. Quota sampling involves stratifying a population into mutually exclusive sub-groups, as if using the stratified sampling method. However, the difference is, in quota sampling, judgement is used instead of randomness to select units from each stratum. The number of sampling units chosen from each stratum is based on proportion. Random sampling is defined as when every unit in the population has a probability of being chosen. For a random sample to be carried out, there also needs to be a sampling frame.

Although quota sampling is criticised heavily by academics, it does have its advantages. The biggest case for it is that is incredibly cheap to carry out. Travel

Middle

(Moser & Stuart, 1953).

We have to also consider the possibility of bias erupting within the quotas at an individual level, leading to misrepresentations of the population. Take for instance; there is a quota for over 60 year olds. If the interviewer only finds people who range from 60 years old to around 65, then there is no representation of people who much older than 65 (Moser & Stuart, 1953).

Another example may be that the interviewer doesn’t like to travel to certain places, therefore only interviews people from a certain area, leading to selection bias in the sample. Random sampling doesn’t have this problem; “Random selection is the only selection mechanism in large-n studies that automatically guarantees the absence of selection bias (Epstein & King, 2002).”

Quota sampling also has the problem of non-response bias, a form of selection bias (selection bias is a non-sampling error). If somebody refuses to be a part of a study, then quota sampling allows the interviewer to go and find the next person who is willing, which results in data that is not wholly representative of the population. The reason for this is, that non-respondents probably have certain characteristics, and because the data obtained from the sample will not represent them at all (it will only be representative of respondents)

Conclusion

(Moser & Stuart, 1953).

To conclude, there is never going to be a complete dismissal of a particular sampling method. Quota sampling has no theoretical structure; however practicality outweighs its negatives. If a researcher is looking for, “results derived from theoretically safe sampling methods,” then it is safe to say that quota sampling is out of the question (Moser & Stuart, 1953). If there are time and cost constraints to a researcher, then quota sampling can be convenient.

WORD COUNT: 1235

References

Epstein, L & King, G. (2002). The Rules of Inference. University of Chicago Law Review. 69 (winter), p1-209.

FAO Corporate Document Respository.  Sampling in Marketing Research. Available: http://www.fao.org/docrep/w3241e/w3241e08.htm. Last accessed 6th December 2010.

Lyman Ott, Mendenhall, Scheaffer, (2006). Elementary Survey Sampling. 6th ed. Canada: Thomson.

Moser & Stuart. (1953). An Experimental Study of Quota Sampling. Journal of the Royal Statistical Society. 116 (4), p412-413 & p387-340.

Tansey, O. (2007). Process Tracing and Elite Interviewing: A Case for Non-Probability Sampling. PS: Political Science & Politics. 40 (4), p770.

This student written piece of work is one of many that can be found in our University Degree Statistics section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related University Degree Statistics essays

1. ## Non-Response Bias

Hence conclusions about the population for which the researcher is interested in will be incorrect. Nonresponse will develop nonsamlping errors but it will also increase sampling error because it reduces the sample size. An example of the impact of nonresponse bias is an article published in December 2006 in 'The Times'.

2. ## Looking at the similarities and differences between jobs and pay that effect the young ...

Data The results I obtained are shown on the attached 'survey data sheet', which shows the thirty results that we recorded at the time. Presentation of Data I have presented this Data in the following formats, using separate diagrams for male and female, where appropriate.

1. ## Research Methods.

For instance, one can code an open-ended interview with numbers that refer to data specific references. Moreover, we can sort respondents' open-ended answers into major themes and code the data quantitatively, thus, calculate the correlation of the themes or the respondents.

2. ## Quantitative Methods

The negative kurtosis means that the distribution is "flat." The standard deviation is similar compared to Johnson and Johnson's shares in this report, but Hewlett Packard's share price has been fluctuated a little bit. General speaking, Hewlett Packard's share price has been relatively stable during the period with a hint of future increases.

1. ## Dress code study. The method of random sampling in this investigation was cluster ...

is to find out the number of ABC University female students who receive summonses during the period June 2005 to June 2006 and the opinions of the students about whether or not the restrictions should be abolished. We have analysed each of the four restrictions under investigation in details.

2. ## Statistics Unit 1 IP

and dividing by the number of groups wanted. The width turned out to be .78 or .8 rounded (3.9/5 = .78). This means that each group will cover .8 such as the group 2.9 through 3.7. I determined the upper boundaries of my groups to be 3.6, 4.4, 5.2, 6, and 6.8.

1. ## Does the data indicate that the revised (one week) forecast is significantly more accurate ...

Excel StatPro package- Chi-square test for data of actual demand As displayed in the above table, the frequency in categoriey of <=1234 is merely 1, which is blow 3. Because the ?2 does not work very well with small frequencies, this category is combined with the below one 1234- 1534, which gives the number of cell k=5.

2. ## The methods I have used to establish that inequalities exist between different wards in ...

A comparison of data from the census was shown using various graphs. Ward maps are essential information detailing the location and boundaries of each ward. Data available from the internet includes deprivation levels in the wards. Scale: 0=very happy 1=happy 2=not bothered 3=unhappy 4=very unhappy How happy are you with the following aspects of the local area?

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to