Unit 3 Collecting Data

Terminology

1. Population: The entire group you're interested in studying.

2. Census: Collecting data from every member of a population.

3. Sample: A smaller group selected from the population.

4. Sample Survey: A study that collects data from a sample of the population.

5. Convenience Sampling: Choosing individuals who are easiest to reach.

6. Convenience Sample: A sample chosen based on ease of access.

7. Bias: A systematic error that leads to inaccurate results.

8. Voluntary Response Sample: A sample made up of people who choose to participate.

9. Random Sampling: A method where every member of the population has an equal chance of being selected.

10. Simple Random Sample (SRS): A sample where every group of a certain size has an equal chance of being selected.

11. Stratified Random Sample: A sample where the population is divided into groups (strata), and a random sample is taken from each group.

12. Strata: Subgroups in a population that share a common characteristic.

13. Cluster Sample: The population is divided into clusters, and entire clusters are randomly selected to be sampled.

14. Clusters: Groups within a population, often based on location or organization.

15. Undercoverage: When some members of the population are not properly represented in the sample.

16. Nonresponse: When individuals chosen for a survey do not respond.

17. Observational Study: A study where researchers observe but do not interfere with the subjects.

18. Experiment: A study where researchers actively change something to observe its effect.

19. Confounding: When the effects of two variables cannot be separated.

20. Confounding Variable: A variable that affects both the independent variable and the outcome, making it hard to tell their true relationship.

21. Treatment: A specific condition applied to the subjects in an experiment.

22. Experimental Units: The individuals or things being studied in an experiment.

23. Subjects: The people being studied in an experiment.

24. Random Assignment: Assigning subjects to treatments using random methods to eliminate bias.

25. The 4 Principles of Experimental Design:

- Comparison: Compare results from different treatment groups.

- Random Assignment: Use random methods to assign treatments.

- Control: Keep other factors constant to isolate the treatment effect.

- Replication: Repeat the experiment to ensure results are reliable.

26. Control Group: The group in an experiment that does not receive the treatment, used for comparison.

27. Placebo Effect: When subjects show improvement simply because they believe they are receiving treatment.

28. Treatment Group: The group in an experiment that receives the actual treatment.

29. Completely Randomized Design: An experiment where subjects are randomly assigned to all treatment groups.

30. Single Blind: When only the subjects or the researchers (but not both) are unaware of who is receiving the treatment.

31. Double Blind: When both the subjects and the researchers are unaware of who is receiving the treatment.

32. Statistically Significant: Results that are unlikely to have happened by chance.

33. Blocking: Grouping experimental units by similar characteristics to reduce variation.

34. Block: A group of similar experimental units.

35. Randomized Block Design: An experiment where subjects are divided into blocks based on a characteristic, and then randomly assigned to treatments within each block.

36. Matched Pairs Design: An experiment where subjects are paired based on similarities, and each pair receives different treatments.