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Probability and Statistics - Tufts University

Terms

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Hypothesis Test
Hypothesize a value (or range of values) for the population characteristic, then asses whether the data supports that hypothesis
Unbiasedness
Expected value should be equal to the desired population parameter (E(stat) = population value)
Efficiency
Variability of stat should be small
Confidence Interval Assumptions
Assume Xi are random and independent
Z or T Confidence Interval Reminders
Use alpha/2
Prediction Interval
Predict a value for future observations of a random variable
Tolerance Interval
Example: 95% confident that 90% of resistors will be between...
Null Hypothesis
Hypothesis which is allowed to stand in the absence of convincing evidence
Alternative Hypothesis
Hypothesis which bears the "burden of proof"
Type I Error, alpha
Probability of falsely rejecting the null hypothesis given that the null is true
Type II Error, beta
Probability of failing to reject the null hypothesis, given that the alternative is true
Operating Characteristic Curve (OC Curve)
Plot of beta versus x-bar which is a graph of type II error
Types of t-tests
Pooled, 2-simple, Paired...for 2-simple, use the funky degrees of freedom equation
Paired Test Pros and Cons
Randomization - if there is a systematic difference in experimental technique, type I error could occur; Paired T is more sensitive, can discern real differences
Conditions for using Paired T-Test
Values must be associated by design, not arbitrarily; experiments designed in pairs, should be analyzed that way
Study Rejection Regions for F-Test
They are kind of funky...Section 9, Page 18
What is (yi - y^i)?
Residual
Method of Least Squares
Select b1 (slope) such that the sum of the squares of the residuals is a minimum
Meaning of P on Exam Notes
P is 2 for straight line

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