{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lecture8 - Psych 100A Lecture 8 Statistical Inference 1...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Psych 100A Winter 2010 Lecture 8: Statistical Inference 1.Interval estimate (recap) 2.Hypothesis testing: tests of significance Example Notations and definitions 3.Test for , known 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
1. Interval estimates How accurate are the point estimates? Example: Suppose a city manager in Los Angeles wants to know the mean income ( ) of 25,000 families living in South Los Angeles. She i t i 900 ( ) f ili “ t d ” d interviews 900 (n) families “at random” and finds that the sample mean = $14,400 . Based on past study, she knows that the population SD ( ) of incomes equals $9,000. P bl P t “ i t k ” b th Problem: Put a “give or take” number on the point estimator (ie, the sample mean). x ? 2
Background image of page 2
Solution: Although the exact distribution of incomes for this community is unknown incomes for this community is unknown, 1. Sampling distribution of mean incomes is normally distributed with mean and ) ( ~ 2 n N x variance 2 /n due to central limit theorem. Or, , 2. Magnitude of chance errors in sample mean when repeatedly drawing a random sample of size 900 from all 25,000 families is 300 $ 000 9 $ 900 , n 3 Chance error in sample mean is called 3. Chance error standard error . 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon