1. Welcome to Stat 200

2. Statistics Data Collection Summarizing Data Interpreting Data
Drawing Conclusions from Data

3. Data Collection Designing experiments Observational studies
Does aspirin help reduce the risk of heart attacks?
Observational studies
Polls - Clinton’s approval rating

4. Summarizing and Interpreting Data
Grade distribution for a college course
Baseball players batting average against left-handed pitchers during night games on artificial turf …

5. Drawing Conclusions Quality control and improvement
Analysis of designed experiments
Analysis of observational studies

6. Time for some
definitions

7. Population
The set of data (numerical or otherwise) corresponding to the entire collection of units about which information is sought

8. Population Examples
Unemployment - Status of ALL employable people (employed, unemployed) in the U.S.
SAT Scores - Math SAT scores of EVERY person that took the SAT during 1997
Responses of ALL currently enrolled underage college students as to whether they have consumed alcohol in the last 24 hours

9. Sample
A subset of the population data that are actually collected in the course of a study.

10. Sample Examples
Unemployment - Status of the 1000 employable people interviewed.
SAT Scores - Math SAT scores of 20 people that took the SAT during 1997
Responses of 538 currently enrolled underage college students as to whether they have consumed alcohol in the last 24 hours

11. Population vs. Sample
Population
Sample

12. WHO CARES?
In most studies, it is difficult to obtain information from the entire population. We rely on samples to make estimates or inferences related to the population.