NormalCurve_ztest 14

NormalCurve_ztest 14 - Normal Curve Introduction The normal...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
Normal Curve Introduction
Background image of page 1

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

View Full DocumentRight Arrow Icon
The normal curve Aka The Bell Curve; The Normal Distribution Example: Individual’s IQ scores
Background image of page 2
68.2% 95.4% 99.6% z-scores = standard deviation units
Background image of page 3

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

View Full DocumentRight Arrow Icon
Normal distribution Mean IQ = 100 Standard deviation = 16 Scores vary +16.0/-16.0 from the mean of 100 84 to 116 Values higher than 116 or lower than 84 are more than one standard deviation away from the mean and would be considered more “extreme” Values that are two or three standard deviations from the mean as “outliers” These very high and very low IQ people are not “typical” of the rest of the population 68% probability that a person’s IQ is between 84 and 116 95% probability that person’s IQ is between 68 and 132 99% probability that person’s IQ is between 52 and 148
Background image of page 4
Area under the curve z-table handout
Background image of page 5

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

View Full DocumentRight Arrow Icon
% above/below z-score Question: Using the z-table, how many people would you expect to score below a z-score of +.75? Answer: 77.34% Question: Using the z- table, how many people would you expect to score above a z- score of - 1.18? Answer: 88.10% Question: Using the z- table, how many people would you expect to score above a z- score of +1.64? Answer: 5.05% Question: Using the z- table, how many people would you expect to score above a z- score of +1.65? Answer: 4.95% Question: Using the z- table, how many people would you expect to score above a z-score of +1.645? Answer: 5%
Background image of page 6
Example One baby compared to population of babies One baby, “Kate”, takes the “My Baby Can Read” program Every dot under the curve is one baby’s reading score (babies not in the program) How does Kate (the baby in the program) compare to babies not in the program?
Background image of page 7

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

View Full DocumentRight Arrow Icon
Example (cont) What if the z-score for Kate’s reading score (the baby in the program) was z = 0? She is no different than babies not in the program. Her score is in the middle of the distribution of no-program kids! Her reading score is not higher (or lower) than babies who were not in the program.
Background image of page 8
SCORE -4 -2 0 2 4 0.0 0.1 0.2 0.3 0.4 34% 34% 14% 14% 2% 2% 50% The area under a normal curve
Background image of page 9

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

View Full DocumentRight Arrow Icon
Example (cont) What if the z-score for Kate’s reading score (the baby in the program) was… z = +.69? She scored higher than 75.49% of the no-program kids. z = +1.20? She scored higher than 88.49% of the no-program kids. z = +1.645 She scored higher than 95% of the no-program kids.
Background image of page 10
z = +.69? She scored higher than 75.49% of the no-program kids. z = +1.20? She scored higher than 88.49% of the no-program kids. z = +1.645 She scored higher than 95% of the no-program kids. How do we know that the program worked???? Maybe Kate is just a really good reader!
Background image of page 11

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

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 57

NormalCurve_ztest 14 - Normal Curve Introduction The normal...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online