Hint 2 answers are correct 4 answers are

Hint, 2 answers are correct 4 answers are incorrect

Details • ********************* • Midterm #1 Tuesday February 3 • Bring: – – Scantron Form F-288 -ERI-L #2 pencil Calculator One page of notes (8 ½ x 11) • ********************* • Homework #1 Due Today in lecture – I will post answers tomorrow

Midterm #1 Review • Laura will do a review session • Friday 1/30 from 1: 00 -2: 00 pm • 4206 SSPB

LARC Tutor http: //www. larc. uci. edu/ Look under Soc Sci ANTHRO 10 B SOCIOL 10 B

Sampling Distribution of the Proportion • Sampling Distribution – Mean – Standard error – Shape • Confidence Intervals for proportion • Margin of error +/- ___% • Reading, Chapter 5, pages 131 -135

Confidence Interval for a Proportion Population proportion Is unknown Estimate the Standard Error

Find the 95% Confidence Interval For the proportion in favor

Find the 95% Confidence Interval For the proportion in favor

. 025 Z = +/ - 1. 96 Why. 025 ?

95% Confidence Interval

95% Confidence Interval

95% Confidence Interval

95% Confidence Interval We can be 95% confident that in the population between. 8004 and. 8396 favor gun permits

Confidence Interval for a Percent • Multiply the proportion by 100

82% favor gun permits

95% Confidence Interval We can be 95% confident that in the population between. 8004 and. 8396 favor gun permits

95% Confidence Interval for the percent in favor We can be 95% confident that in the population between 80. 04% and 83. 96% favor gun permits

95% Confidence Interval for the percent in favor 82% favor gun permits

95% Confidence Interval for the percent in favor We can be 95% confident that in the population 82% plus or minus 1. 96% favor gun permits

Stopped here on Tuesday 1/27

• Confidence interval and confidence level 90% confidence 95% confidence 99% confidence

90% Confidence Interval for the proportion in favor

90% Confidence Interval for the proportion in favor

90% Confidence Interval for the proportion in favor

90% Confidence Interval for the percent in favor 82% plus or minus 1. 65%

99% Confidence Interval for the proportion in favor

99% Confidence Interval for the proportion in favor

99% Confidence Interval for the proportion in favor

99% Confidence Interval for the percent in favor 82% plus or minus 2. 58%

People in the US are not in favor of gun permits I don’t think that’s correct

Do adults in the US oppose gun permits? In fact, I’m very confident people FAVOR gun permits

Margin of Error It seems like this is often plus or minus 3% Why is that?

http: //www. pollingreport. com/race. htm#Immigration

Margin of Error • • Plus or minus some % Around the sample statistic Includes the population parameter With a given level of confidence

A Problem …. . Margin of Error • For N = 1000 • With confidence level = 95% • How wide is the margin of error? +/- ______% • Assume population proportion =. 5

Sampling Distribution of the Proportion

Sampling Distribution of the Proportion 95%

Sampling Distribution of the Proportion 95%

Sampling Distribution of the Percent 95%

Sampling Distribution of the Percent 95%

http: //www. pollingreport. com/race. htm#Immigration

Another Confidence Interval Example • Do a majority of adults in the US like classical music? • How confident can you be of that conclusion?

General Social Survey 1993

General Social Survey 1993

General Social Survey 1993

Can we be confident that a majority of people like classical music? General Social Survey 1993

80% Confidence Interval

80% Confidence Interval

80% Confidence Interval

80% Confidence Interval

80% Confidence Interval Z = +/ ? Where should I look?

80% Confidence Interval . 10 Z = +/- 1. 28 Where should I look?

80% Confidence Interval

80% Confidence Interval From. 4902 to. 5158 This interval includes the possibility that less than a majority like classical music

70% Confidence Interval Maybe if we are willing to be a little less confident, we can conclude that a majority like classical music

70% Confidence Interval

70% Confidence Interval . 15 Z = +/- 1. 04 Where should I look?

70% Confidence Interval

70% Confidence Interval From. 4926 to. 5134 Even this interval includes the possibility that less than a majority like classical music

60% Confidence Interval Maybe if we are willing to be even less confident, we can conclude that a majority like classical music

60% Confidence Interval

60% Confidence Interval Z = +/- 0. 84 . 20 Where should I look?

60% Confidence Interval

60% Confidence Interval From. 4946 to. 5114 Even this interval includes the possibility that less than a majority like classical music

Confidence Interval Example • Do a majority of adults in the US like classical music? • How confident can you be of that conclusion?

Confidence intervals for the proportion who like classical music 80% CI from. 4902 to. 5158 70% CI from. 4926 to. 5134 60% CI from. 4946 to. 5114 . 495 . 505 . 515

Ace that Midterm !!!

Population standard deviation

95%

99% confidence interval is from. 43 to. 49 identifying as middle class

99% confidence interval is from. 43 to. 49 identifying as middle class

99% confidence interval is from. 43 to. 49 identifying as middle class I’m 99% confident ……

. 025 Z = +/ - 1. 96 Where should I look?

Another Confidence Interval Example • Do people favor or oppose sex education in the public schools?

General Social Survey 1993

General Social Survey 1993