1. © Copyright McGraw-Hill 2004 1-1 Observational and Experimental Studies In an observational study, the researcher merely observes what is happening or what has happened in the past and tries to draw conclusions based on these observations. In an experimental study, the researcher manipulates one of the variables and tries to determine how the manipulation influences other variables.

2. © Copyright McGraw-Hill 2004 1-2 Uses and Misuses of Statistics Suspect samples  Very small samples  Bias sample selection  Volunteer samples Ambiguous averages Changing the subject

3. © Copyright McGraw-Hill 2004 1-3 Uses and Misuses of Statistics (cont’d) Detached statistics Implied connections Misleading graphs Faulty survey questions

4. © Copyright McGraw-Hill 2004 1-4 Computers and Calculators In the past, statistical calculations were done with pencil and paper. However, with the advent of calculators, numerical computations became easier.

5. © Copyright McGraw-Hill 2004 1-5 Statistical Packages Excel, MINITAB, and the TI-83 graphing calculator can be used to perform statistical computations. Students should realize that the computer and calculator merely give numerical answers and save time and effort of doing calculations by hand.

6. © Copyright McGraw-Hill 2004 1-6 Conclusion The applications of statistics are many and varied. People encounter them in everyday life, such as in reading newspapers or magazines, listening to the radio, or watching television.