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Stat 200 Exam 1 Study Guide

• Chapters 1-4

Statistics

• a collection of procedures and principles for gathering data and analyzing information to help people make decisions when faced with uncertainty

Discovery of Knowledge

• 1. Asking the right questions
• 2. Collecting useful data
• 3. Summarizing and analyzing data
• 4. Making decisions and generalizations
• 5. Turning the data and subsequent decisions into new knowledge

Moral of the Story

• simple summaries of data ----> interesting story/easier than longer list
• when reading about change in rate/risk of occurrence ----> ask for base rate/baseline risk
• representative sample of a few thousand/hundred can give accurate information about a population of millions
• unrepresentative sample tells nothing about population
• cause and effect conclusions: can be made from randomized experiments, cannot be made from observational studies
• statistically significant findings are not necessarily practically significant, find out the magnitude of the relationship or difference
• find a study with a relationship or difference ----> find out how many things were tested (more tests+ more likely that the statistically significant finding was a false positive (explained by chance))

Raw Data

• term for numbers/category labels that have been collected but not yet processed
• example: how many hours did you sleep? raw data: 5

Variable

• characteristic that can differ from one individual to the next
• example: sex, hours of sleep, choice of letter, height

Observational Unit

• single, individual entity (observation- value of single measurement; height)
• example: person in a study

Sample Size

• total number of observational units
• represented by "n"
• example: 190 students in study n= 190

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