(Midterm) Z score

Question 1

What is the primary purpose of a z-score?

Answer 1

To describe the exact location of a score within a distribution.

Question 2

The numerical value of the z-score corresponds to the _____________________

Answer 2

number of standard deviations between X and the mean of the distribution.

Question 3

Z-scores identify ____________ within a distribution means.

Answer 3

exact locations

Question 4

Z-scores can be used as ____________________ & ________________________

Answer 4

descriptive statistics and as inferential statistics.

Question 5

As ___________, z-scores determine whether a specific sample is representative of its population, or is extreme and unrepresentative.

Answer 5

inferential statistics

Question 6

What is the advantage of standardizing distributions?

Answer 6

Two (or more) different distributions can be made the same.

Question 7

Probability is the ______________________.

We define probability as a fraction or a proportion.

Answer 7

Method for measuring and quantifying the likelihood of obtaining a specific sample from a specific population

Question 8

The probability of any specific outcome is determined by a ________________

Answer 8

Ratio comparing the frequency of occurrence for that outcome relative to the total number of possible outcomes. (Fo/Po)

Question 9

When a population of scores is represented by a frequency distribution, probabilities can be defined by_____________

Answer 9

proportions of the distribution.

Question 10

In graphs, probability can be defined as a _______________

Answer 10

proportion of area under the curve.

Question 11

Why is probability important?

Answer 11

Probability is important because it establishes a link between samples and populations.

Question 12

What is the general goal of inferential statistics?

Answer 12

To use the information from a sample to reach a general conclusion (inference) about an unknown population.

Question 13

Two requirements of a random sample

Answer 13

1. Each individual in the population has an equal chance of being selected
2. If more than one individual is to be selected for the sample, there must be constant probability for each selection

Question 14

What is the definitions of “distribution of sample means”?

Answer 14

the set of X‘s for all the possible random samples a specific sample size (n) that can be obtained from a given population

Question 15

The parameters of the distribution of sample means (acc to central limit theorem):
1.
2.
3.

Answer 15

1. shape (normal, n=30 or more)
2. central tendency
3. variability

Question 16

What do you call the mean of the distribution of sample mean?

Answer 16

Expected value of X

Question 17

The standard deviation of the distribution of sample means is called the _______

Answer 17

standard error of X

Question 18

What does the standard error do?

Answer 18

Measures the standard distance between a sample mean and population mean

Question 19

The________tells how much error to expect if you are using a sample mean to estimate a population mean

Answer 19

standard error

Question 20

State the law of large numbers

Answer 20

The larger the sample size (n), the more probable it is that the sample mean will be close to the population mean

Question 21

______________ involves using sample statistics to make a general conclusion about a population parameter. The standard error plays a crucial role in inferential statistics

Answer 21

Statistical inference

Question 22

____________________ is an inferential procedure that uses the data from a sample to draw a general conclusions about population.

Answer 22

Hypothesis testing

Question 23

4 steps of hypothesis testin

Answer 23

1. State the null hypothesis
2. Locate the critical region
3. Collect the data, and compute the test statistics
4. Make a decision

Question 24

Two types of errors that can be committed

Answer 24

Type I error

Type II error

Question 25

Occurs when a researcher rejects a null hypothesis that is actually true

Answer 25

type I error

Question 26

Occurs when a researcher fails to reject a null hypothesis that is really false

Answer 26

type II error

Question 27

When do we use one tailed tests?

Answer 27

> When a researcher predicts that a treatment effect will be in a particular decision (increase or decrease)
When there is a prior justification for making a directional prediction.

Question 28

What is the probability that the test will correctly reject the null hypothesis.

Answer 28

Power of the hypothesis test

Question 29

As the size of the treatment effect increases, statistical power ______

Answer 29

increases

Question 30

FACTORS THAT CAN INFLUENCE POWER

Answer 30

A. increasing alpha level
B. A one tailed test will have greater power than a two tailed test
C. A large sample will result in more power than a small sample