Chapter 7- Theoretical Distributions Including the Normal Distribution

Question 1

Probability

Answer 1

The chance that something can occur

They are often stated as “chances in a hundred”
Ex. p = 0.07 means you have a 7 percent chance in 100

Question 2

How do you calculate probability?

Answer 2

1. Enumerate all the ways a success can occur
2. Then enumerate all the events that can occur (whether successes or failure)
3. Finally, form a ratio with successes in the numerator and total events in the denominator

Example:
A fair coin is tossed 2 times, what is the probability of 1 head and 1 tail?

1. 2
2. 4
3. 2/4 Probability = 0.5

Question 3

Properties you have to remember about probability

Answer 3

1. It is ALWAYS greater than or equal to zero

2. IT IS VERY VERY VERY EASY TO CONFUSE the number of possible CATEGORIES v the number of possible OUTCOMES

Question 4

What is the area under a normal distribution curve equivalent to?

Answer 4

Proportion of z-scores in that part of the distribution

Question 5

Empirical distribution

Answer 5

scores that come from observations

the empirical approach to finding probability involves observing actual events, some of which are successes and some of which are failures

Question 6

Theoretical distribution

Answer 6

Hypothesized scores based on mathematical formulas and logic
Used in statistics to determine probabilities

Question 7

Normal Distribution

Answer 7

A bell-shaped, theoretical distribution that predicts the frequency of occurrence of chance events

Question 8

Z score

Answer 8

A raw score expressed in standard deviation units

Question 9

The tails of the normal distribution curve are

Answer 9

Asymptotic. Meaning they never actually cross the x axis but continue in both directions indefinitely

Question 10

The normal distribution’s inflection points are where?

Answer 10

At +/- 1baby sigma. Inflection points are where the curve is the steepest– that is, where the curve changes from bending upward to bending over