AS Stats Chapter 1: Data Collection

32 flashcards · Mathematics · by TheoTyson

1. What is a population?

   The whole set of items that are of interest.

2. What is a census?

   Observes or measures every member of the population.

3. What is a sample?

   Observations taken from a subset of the population to find out information about the whole population.

4. What is the advantage of a census?

   The result is perfectly accurate.

5. What are the disadvantages of a census?

   Time consuming and expensive. Could destroy the population.

6. What are the advantages of a sample?

   Not time consuming and less expensive. Less data to collect and process.

7. What are the disadvantages of a sample?

   Data not as accurate. The sample may not represent the whole.

8. What are sampling units?

   Individual units of a population.

9. What is a sampling frame?

   A numbered or ordered list of sampling units.

10. What is a simple random sample?

    A sample where every sample has an equal chance of being selected from randomly generated numbers.

11. What are the advantages of a simple random sample?

    Free of bias as each unit has an equal chance. Easy and cheap to implement.

12. What are the disadvantages of a simple random sample?

    A sampling frame is needed. The entire population size is needed.

13. How is lottery sampling carried out?

    The members of the sampling frame could be place into a hat and then randomly selected.

14. What is a systematic sample?

    A sample where required elements are chosen at regular intervals from an ordered list.

15. What are the advantages of a systematic sample?

    Simple and quick to use. Suitable for large samples.

16. What are the disadvantages of a systematic sample?

    A sampling frame is needed. It can introduce bias if the frame is not random.

17. What is a stratified sample?

    A sample where the population is divided into mutually exclusive strata and a random sample is taken from each.

18. What are the advantages of a stratified sample?

    Accurately reflects the population structure. Guaranteed proportional representation.

19. What are the disadvantages of a stratified sample?

    Population must be split into strata. Each stratum must have a random sample.

20. What is a quota sample?

    The sample is taken that reflects the characteristics of the whole population. Allocating data into groups until the quota is full.

21. What are the advantages of a quota sample?

    No sampling frame required. Allows for comparison between different groups.

22. What are the disadvantages of a quota sample?

    Population must be divided into groups. Non random sampling can introduce bias.

23. What is an opportunity sample?

    Taking the sample from people who are available at the time the study is taken.

24. What are the advantages of an opportunity sample?

    Easy to carry out. Inexpensive.

25. What are the disadvantages of an opportunity sample?

    Unlikely to provide representative sample. Highly dependent on sample taker.

26. What is quantitative data?

    Data with numerical values.

27. What is qualitative data?

    Data with non-numerical values.

28. What is continuous data?

    Data that can taken any value in a given range.

29. What is discrete data?

    Data that can only take specific values in a given range.

30. What is the class boundary?

    The maximum and minimum values that belong in the class.

31. What is the midpoint?

    The average of the class boundaries.

32. What is the class width?

    The difference of between the upper and lower class boundaries.