Quota sampling might be the only real possibility. If there is no sampling frame (list of sampling units), the above sampling methods can"t really be implemented. It doesn"t matter how they choose the 50, as long as they interview that many. For example, if someone is interviewing people at a shopping centre, they may have been told to interview 50 men and 50 women. This method is easy to implement when carrying out market research. Quota sampling involves splitting the population into groups and sampling a given number of people from each group. In the television example, if children make up 20% of the population, we would make sure that children make up 20% of the total sample. For example, if we were trying to find the nation"s favourite television programme, most children would probably like different programmes to most adults.Įach group is sampled separately and the results are put together. Stratified sampling can be used when the population in question is split up into groups who are likely to behave differently. For example, every 10th member of the sample frame could be selected. Instead of choosing the members to be sampled using random numbers (which might be difficult and time consuming for large populations), systematic sampling uses a simple rule to choose people. Random numbers are then generated (using a computer or from a table) and those members of the sample frame whose numbers come out are sampled. One way of doing this is to assign each member of the sample frame a number. The idea of random sampling is that each member of the sample frame has an equal chance of being selected. The video below explains the four types of sampling and gives an example of how a Two-Way table can be used in exam questions. Ideally, this should cover the whole population. For example, if we were trying to find out how many cars the average family owns, the sampling unit would be a household rather than an individual, because we wouldn"t want to ask two people from the same household.Ī sampling frame is the collection of all of the sampling units. The sampling units must be defined in such a way that any one member of a population is not sampled more than once. Instead, 1000 people might be chosen and asked.Ī sampling unit is a person/object to be sampled. For example, if we were trying to find out what Britain"s favourite TV show is, it would be impractical to ask everybody in the country (as a census would do). The disadvantage of this method is that if the population is large, it can be difficult to collect and process so much information.Ī sample surveyis when information is collected from a small representation of the population. It might be a group of people or it could be simply a group of numbers.Ī censusis when information about every member of the population is collected. Topics include populations, census, sample surveys, sampling units, sampling frames, Random Sampling, Systematic Sampling, Stratified sampling and Quota samplingĪ populationis a group that we want to find information about. Your list has now been randomly sorted, and you can select the first 10 or 200-whatever you need your sample size to be-and that’s the list of your randomized participants.This section covers Sampling.Sort by the column with the random numbers.Highlight the columns with data and numbers in them.To qualify as being random, each research unit (e.g., person, business, or organization in your population) must have an equal chance of being selected. It is also sometimes called random sampling. This removes the random function from the cells Probability sampling is a sampling method that involves randomly selecting a sample, or a part of the population that you want to research.Highlight the random numbers again and right-click on them.Highlight all random numbers in the Random_number column.To prevent the numbers from changing as you work with the table:.Drag the small box at the bottom right corner of the cell and drag the box down the column to the bottom of the list-this generates a new random number for each name on your list.Select the cell with the new random number in it. Press enter and a random number will appear in the selected cell.In the first row under the heading row, in the Random_number column, enter the formula =RAND().Make a third column for the email addresses of each customer.Add a new column to the right and name it Random_number.Enter the names of the customers you have contact information for in the first column.
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