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SAMPALING
Research Methodology
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You have to first know what you are looking for -this is not always so easy.
If your new chocolate bar isnt selling well, youdont automatically do market research on thetaste - because maybe the reason has to do
with the packaging.
Problem Definition
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hypothesis
After the problem has been defined;(Step 1), and an exploratory
investigation (Step 2), has beenconducted, it is possible to thenformulate a Hypothesis (Step 3)
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A tentative explanation about therelationship between variables as a startingpoint for further testing .
The way of thinking about how somethingworks - and using your original guess as astarting point for further investigation
Hypothesis
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The selection of areas considered reasonably typicalof the total market, and introducing a new product tothese areas with a total marketing campaign todetermine consumer response before marketing theproduct nationally.
Test Marketing
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What is a sample ?
A subset of some of the units in the populationA subgroup of the population
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Example
population size = 1000 ( blue collar)
Sample size = 200
(chosen for studying performance of blue collar)
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Why sampling ?
Too expensive to test the entire populationImpossible to test entire population
Testing the entire population often produceserrorsMay give accurate results
Enables to researchers to make estimates of some unknown characteristics of population inquestion
High scope of accuracy and reliability
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Sampling Methods
Probability Non-Probability
Based on probability theory. Focus on volunteers, easily
available units, or those that justhappen to be present when theresearch is done.
Every unit of the population of
interest must be identified, andall units must have a known,non-zero chance of beingselected into the sample.
Useful for quick and cheap
studies, for case studies, forqualitative research, for pilotstudies, and for developinghypotheses for future research.
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Probability
Simple random sample
Systematic random sampling
Stratified random samplingCluster sampling
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Simple random sampling
Population = nSample = nAll possible sample= n
A random number table is a list of numbers, composedof the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Numbers in thelist are arranged so that each digit has no predictablerelationship to the digits that preceded it or to the digitsthat followed it. In short, the digits are arrangedrandomly. The numbers in a random number table arerandom numbersLink - http://stattrek.com/Tables/Random.aspx
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Simple random sampling
25 Random Numbers068 057 036 098 014 015 012 022 094 080094 052 077 076 006 013 018 002 051 080066 035 000 004 044
* This table of 25 random numbers was produced according to the followingspecifications: Numbers were randomly selected from within the range of 0 to 100.Duplicate numbers were allowed.
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Systematic Random sampling
most appropriate practical method forsampling
for instance - to select every X th item fromthe list.
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Systematic Random sampling
There is a population of 2000 and sample size is 100. apply thesystematic random sampling.
Identify Population size = NSample size = n= 100Interval =k=?
k= N/n = 2000/100 = 20
Now Select a random number x between 1 and k.
Suppose first x th number is 12Then next number is = x+k = 12+20 = 32 so on
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Question
Population of people going to night-clubs is onan average about 250-300 people in a city.Number of night clubs are 30.
A researcher wants to select people forinterview among this population .Applysystematic random sampling to identify thepeople.
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Stratified sampling
Constructed by classifying the population in sub-populations (or strata), base on some well-known characteristics of the population, such asage, gender or socio-economic status.
The selection of elements is then madeseparately from within each strata, usually byrandom or systematic sampling methods.
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Example
Sample size = n = 30
Population size =N= 8000
Population is divided into three strata ;
N1= 4000 , N 2= 2400 , N 3= 1600
Find the sample sizes for the different strata by using proportional allocation : For Proportional Allocation
P1 = 30 (4000/8000) = 15
P2 and P 3 = ??
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Question
In the class 12 th , pupils are offered Maths,Physics or Chemistry homework. 28 chooseMaths homework 47 choose Physicshomework 25 choose Chemistry homework. If you wanted to check the homework of any 20students, how many of each would you
choose? ..
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Cluster
Suitable for conducting research studies thatcover large geographic area.
Once the cluster is formed the researcher caneither go for one stage, two stages, or multistage cluster sampling.
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Example
Suppose that the Department of Agriculture wishesto investigate the use of pesticides by farmers inEngland.
A cluster sample could be taken by identifying thedifferent counties in England as clusters. A sample of these counties (clusters) would then bechosen at random, so all farmers in those countiesselected would be included in the sample. It iseasier to visit several farmers in the same countythan it is to travel to each farm in a random sampleto observe the use of pesticides.
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Non-Probability
Convenience sample Purposive sample Quota sample
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Convenience
An exploratory research where the researcheris interested in getting an inexpensiveapproximation of the truth. As the nameimplies, the sample is selected because theyare convenient.
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Purposive
The researcher selects the units with somepurpose in mind, for example, students wholive in dorms on campus, or experts on urbandevelopment.
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Quota
widely used in opinion polling and marketresearch.Interviewers are each given a quota of subjectsof specified type to attempt to recruit forexample, an interviewer might be told to go outand select 20 adult men and 20 adult women,
10 teenage girls and 10 teenage boys so thatthey could interview them about their televisionviewing.
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Differences between ProbabilitySampling and Non-Probability
Probability (Random) Sampling Non-Probability (Non-Random)Sampling
Allows use of statistics, testshypotheses
Exploratory research, generateshypotheses
Can estimate populationparameters
Population parameters are not of interest
Eliminates bias Adequacy of the sample can't beknown
Must have random selection of units
Cheaper, easier, quicker to carryout
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Steps in Sampling Design
Type of universe: The universe can be finite orinfinite. In finite universe the number of items iscertain, but in case of an infinite universe (citypopulation, factory workers etc,) the number of items is infinite, i.e., we cannot have any ideaabout the total number of items ( number of stars).Sampling Unit: Sampling Unit may be geographicalone such as state, district, village, etc., or aconstruction unit such as house flat., it may beindividual.
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Steps in Sampling Design (contd..)
Source list : It is also known as samplingframe from which sample is to be drawn. Itcontains the names of all items of a universe
(incase of finite universe only). If the sourcelist is not available, the researcher has toprepare it. Such list should be comprehensive,correct, reliable and appropriate. It isextremely important for the source list to beas representative of the population aspossible.
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Steps in Sampling Design (contd..)
Size of sample : The sample size should neither beexcessively large, nor too small. It should be optimum.An optimum sample is one which fulfills the
requirements of efficiency, appropriate representation,reliability and flexibility. While deciding the sample size,researcher must determine the desired precision as alsoan acceptable confidence level for the estimate.
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Steps in Sampling Design (contd..)
Parameters of interest: In determining the sampledesign, one must consider the question of thespecific population parameters which are of interest. For instance, we may be interested inestimating the proportion of persons with somecharacteristic in the population, or we may be
interested in knowing some average or the othermeasure concerning the population.
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Steps in Sampling Design (contd..)
Sampling procedure: Finally, the researchermust decide the type of sample he will use
i.e., he must decide about the technique to beused in selecting the items for the sample. Infact, this technique or procedure stands forthe sample design itself. There are severalsample design out of which the researchermust choose one for his study.
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Definition
A set of routine procedures to continuously collect,monitor, and present internal and externalinformation on company performance andopportunities in the marketplace.
Marketing Information Systems
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For some companies, market knowledge comes in on a regularbasis.
Some stuff is Data, and some is Information
Data = statistics, opinions in surveys, facts, predictions etc.
Information = data RELEVANT to the Marketing Manager inmaking decisions
Marketing Information Systems
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All of this depends on the ability of thecompany to use technology to help it be
better than the competition
Marketing Information Systems
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THANK YOU