1. MA 102 Statistical Controversies Wednesday, February 13, 2002 Today: Discuss of data ethics, and exercises Measuring: Turning ideas to numbers Exercise on bias and reliability Reading (for Friday): Chapter 8: Measuring Exercises: 8.1, 8.2, 8.3, 8.5, 8.8, 8.9, 8.19, 8.20, 8.24

2. Measuring: Key Terms To measure something Valid measure Predictive validity Instrument Errors in measurement:  Bias  Random error – reliability

3. Measuring: Some Ideas Rates often give better measures than counts. Examples : auto deaths, unemployment To reduce bias, use a better instrument. To improve reliability, use a better instrument and average your measurements. Example: Measuring the wall