Statıstıcs Iı Deneme Sınavı Sorusu #974072
Which one of the following is not one of the reasons of sampling?
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Cost |
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Time |
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Average |
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Accuracy |
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Destructive tests |
Reasons Of Sampling
When we try to obtain some information about the characteristics of a population there are important reasons why we use a sample instead of a census. The main reasons for sampling can be categorised by the following topics:
Cost
Every project has a limited funding.
Time
A sampling survey often provides more timely information than a census, because fewer data have to be collected and analysed. Thus, the required information can be achieved quickly.
Accuracy
While a census data is gathered, many unexpected problems may affect the accuracy of the results such as recording errors, copying errors, false recordings by interviewers etc. So, while working with census data, we may inadvertently come across with a figure for a population parameter being further away than the actual value. With a good sampling procedure using good sampling methods and by choosing random observations, actually we can be very close to the true value of the population parameter.
Physical Impossibility
Some populations are uncountable or infinite to conduct a census. In this situation, it is impossible to consider all the elements of a population. Thus, a sample is necessary to obtain information from a population.
Destructive Tests
If a test includes the destruction of an item or product, sampling should be used. For example, when a car manufacturer would like to get a safety rating on their cars, they send a selection of cars (3 to 5 cars) to the safety agency for testing and these cars goes under different test including a crash which demolishes the car.
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