STAT 2000 Lecture Notes - Lecture 1: Observational Study, Aspirin, Simple Random Sample
23 Feb 2017
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January 6, 2017-January 11, 2017
Chapter One: Learning from Data
1.1 Defining Statistics
• Statistics= a way of reasoning
• Statistical Method
o Design: refers to how data is obtained
o Description: summarizing data
o Inference: making decisions or predictions based on data
▪ Depends upon our ability to understand variation
• Learning from Data
o Data= information (numbers and words)
o Learn from data by analyzing it and making inferences
• Example 1: Aspirin and Heart Attacks
o Design: 22,000 male physicians; randomly assigned
o Description: two percentages=summarization of data/results
o Inference: generalization that taking aspirin reduces risk of having heart attack
1.2 Population and Samples
• Population= set of all individuals we are interested in studying
• Samples= subset of pop. for whom we have data
• Subjects= things/individ. who make up sample
• Parameter= numerical value summarizing pop. data
• Statistic= numerical value summarizing sample data
o Sample stats estimate for pop. parameter
• Symbols
Population mean
(parameter)
mu
Sample mean (stat)
x-bar
Pop. proportion
(parameter)
P
Sample proportion (stat)
p-hat
• Proportion: another way to express a percentage
o Must be between 0-1
o 50%→0.5
Chapter 4: Gathering Data
4.1: Experimental and Observational Studies
• Two ways to collect data
o 1. Conduct an experiment
o 2. Observational study
• Experiments: attempt to manipulate or influence the subjects to obtain data
o Randomly assigned groups (control and treatment groups)
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