Statistics

Statistics Descriptive Statistics

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

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

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

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

# 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

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

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

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

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