2. Statistics

3. Statistics
Descriptive
Statistics

5. Practice
Based on a sample of participants, it appears that a new drug will be effective at stopping headaches
The enrollment in this course as of August 15th was 22

6. Practice On your first test you received a score of 84 out of 100
Markey will likely be the next president; of the 100 people surveyed 82% said they would vote for him

7. Inferential Statistics
Problem: Is that going to be the exact answer?
Chance influences the sample
“true” variation
“error” variation
Sample = “true” + “error”

8. Understanding Randomness
What is the probability that among 23 people (this class) there will be a shared birthday?

10. # people required(i.e. n) when m=365
The number of people required so that the probability that some pair will have a birthday separated by k days or fewer will be higher than 50% is: k
# people required(i.e. n) when m=365 23 1 14 2 11 3 9 4 8 5 6 7

11. Basic Terms Population Sample Consists of all the scores of some group
Is a subset of a population

12. Basic Terms Parameters Statistics
A numerical or nominal characteristic of a population
Statistics
A numerical or nominal characteristic of a sample

13. Basic Terms Variable Quantitative Variable
Something that exists at more than one amount
Quantitative Variable
A score attached to a variable -- tells you something about its amount

14. Qualitative Variable Are not continuous like quantitative variables
They are usually words or names
e.g., gender, political party, religion