Chapter 5: Normal Distribution Standard Scores

Question 1

When data is graphed it tends to naturally take what shape? List characteristics? (2)

Answer 1

• normal distribution -most points fall in centre, fewer towards extremes

Question 2

What is an example of the naturally occurring standard distribution?

Answer 2

• Galton Board

Question 3

What are the four characteristics of Normal Distribution?

Answer 3

1. symmetrical and bell-shaped 2. mean, median mode 3. asymptotic= extends forever without touching axis 4. area under the curve equals one

Question 4

What are the two parameters of Normal Distribution?

Answer 4

1. mean 2. standard deviation

Question 5

What are the normal distribution probabilities for 1, 2 and 3 standard deviations?

Answer 5

+/- 1= 68% +/- 2= 95% +/- 3= 99% anything after that is ~100%

Question 6

What is a Z score?? (2)

Answer 6

1. A score that indicates how many standard deviations a raw score deviates from the mean 2. Comparisons relative to other participants

Question 7

How do you interpret a Z score? (2)

Answer 7

1. Sign indicates above or below the mean ( left or right) 2. Magnitude indicates typical or atypical score!

Question 8

What is an Atypical score and a typical score?

Answer 8

1. Atypical- outlier…not close to the mean… 2. Typical- closer to the mean…zero

Question 9

What is the standard scores (z-scores) equation for populations and samples?

Answer 9

X=raw score to be standardized

X bar= mean of population

o= standard deviation of population

*** difference between z score pop and z score sample is that the z score sample has a S!…

Question 10

Z scores are generally what?

Answer 10

• unit free…..allowing one to compare distributions that have different units…

Question 11

Standard scores ( z scores) characteristics?

(3)

Answer 11

1. How many SD’s a raw score varies from the mean
2. Directionality (+/-) = above or below mean
3. Magnitude = close or far from mean…

Question 12

With every Z score question you should draw what??

Answer 12

-standard distribution curve ! to help with solving the question..

Question 13

You can rearrange the z score formula to also solve for?

Answer 13

• the raw score…..

Question 14

Z scores can determine the area associated with z scores and therefore the __________ are also possible to find.

The percentages of scores __ or ____ a given raw score.

Answer 14

• percentile rank
• at, below

Question 15

When looking at a Zscore chart……What does Comumn A, B and C represent?

Answer 15

• A: z score ( always positive )
• B: area between mean and z score
• C: area beyond the z score