1. Section 1.3 Introduction to Experimental Design 1.3 / 1

2. Planning a Statistical Study Identify individuals of interest. Specify variables, protocols, procedures. Specify variables, protocols, procedures. Decide on sampling method, if appropriate. Address ethics and privacy issues. Address ethics and privacy issues. Collect data. Collect data. Use descriptive and inferential statistics to make decisions. Note any concerns and recommendations. Note any concerns and recommendations. 1.3 / 2

3. Methods of Producing Data Census Sampling Simulation Experimentation Observation 1.3 / 3

4. Methods of Producing Data Census: Using measurements from the entire population Sampling: Draw a part of the population Simulation: Numerical facsimile of real-world phenomena Observational Study: Observations and measurements of individuals are conducted in a way that does not change the response or the variable being measured Experiment: A treatment is deliberately imposed on the study individuals in order to observe a possible change in the response or variable being studied. 1.3 / 4

5. Placebo Effect A subject receives no treatment but (incorrectly) believes he or she is receiving treatment and responds favorably 1.3 / 5

6. Randomized Two-treatment Experiment Placebo effect is common in medical experiments. Subjects divided into two groups. One group receives actual treatment. Control group receives placebo treatment disguised as real. After treatment cycle, conditions of groups are compared. 1.3 / 6

7. Double-blind Experiment Neither individuals in study nor observers know which subjects are receiving actual treatment. Helps control for subtle biases. 1.3 / 7

8. To prevent bias or inaccurate results Use a control group. Assign individuals to groups randomly. Replicate experiment many times to insure differences did not occur by chance. 1.3 / 8

9. Lurking or Confounding Variables underlying cause Known or unknown variables that might be an underlying cause of a change in response in experimental group. need for control Reason for need for control group 1.3 / 9

10. Potential Problems Strong opinions may be over-represented if responses are voluntary. A hidden bias may exist because of the way data is collected. There may be hidden effects of other variables. There is no guarantee that results can be generalized. 1.3 / 10

11. TI-84Plus / TI-83Plus To select a random set of integers between two specified values, press MATH highlight PRB then press 5. Example RandInt (1, 100, 5) (63 89 13 46 47) RandInt (1, 100, 5) (29 82 99 50 41) 1.3 / 11