Textbook Notes
(359,268)

Canada
(156,147)

University of Guelph
(11,796)

Psychology
(3,237)

PSYC 1010
(57)

c
(11)

Chapter 7

# Chapter 7.docx

Unlock Document

University of Guelph

Psychology

PSYC 1010

c

Fall

Description

Chapter 7- Hypothesis Testing with Z Scores
- Z Test- a hypothesis test in which we compare data from one sample to a
population for which we know the mean and the standard deviation
Z Table
- Provides the percentage of scores between the mean and a given z value
- The key to standardization- allows us to translate the standardized z
distribution into percentages and individual z scores into percentile rankings
- Normal Distributions
About 68% of scores fall within one z score of the mean
About 96% of scores fall within two z scores of the mean
Nearly all scores fall within three z scores of the mean
- Three different ways to identify the same point beneath the normal curve :
Raw score
Z score
Percentile ranking
- Determining the % associated with a given z statistic :
Convert a raw score into a z score
Look up a given z score on the z table to find the percentage of scores
between the mean and that z score
- Calculating the percentile for a positive z score
To find the percentage of scores below a certain score : add the
percentage between the mean and the positive z score to 50%, which
is the percentage of scores below the mean
- Calculating the percentage above a positive z score
Subtract the percentage between the mean and the positive z score
from 50%, which is the full percentage of scores above the mean
- Calculating the percentage at least as extreme as our z score
Double the % that are extreme enough to be below a z score to find
the total percentage of heights that are as far as or farther from the
mean as the z score
- Calculating the percentile for a negative z score
Subtract the percentage between the mean and the z score from 50%,
the total percentage below the mean
- Calculating the percentage above a negative z score
Add the percentage between the mean and the negative z score to
50%, the percentage above the mean
- Calculating a score from a percentile
Calculate the percentage between the mean and the z score
Look up that percentage on the z table- find the associated score
Convert the z score to a raw score using the formula X=z (
Z Table and Distribution of Means - The z table can also be used to determine percentages and z statistics for
distributions of means
- First calculate the mean and the standard error of the distribution of means :
M=
M=
√
- We can then calculate the percentage
Convert a z statistic using the mean and standard error that we just
calculated
Determine the percentage below this z statistic
The Assumptions and Steps of Hypothesis Testing
- Assumptions- characteristic that we ideally require the population from
which we are sampling to have so that

More
Less
Related notes for PSYC 1010