Midterm 2

Question 1

Rectangle shaped probability distribution is called:

Answer 1

UNIFORM distribution

Question 2

The symbol u represents?

Answer 2

Population Mean

Question 3

What does the symbol s^2 represent?

Answer 3

Sample variance

Question 4

A bell-shaped curve is called:

Answer 4

A NORMAL Distribution

Question 5

What does a z-score indicate?

Answer 5

How many standard deviations from the mean an observation is located.

Question 6

How many standard deviations is the 95% confidence limits from the mean?

Answer 6

2

Question 7

Why are normal distribution so important?

Answer 7

Many dependent variables are commonly assumed to be normally distributed in the population and if a variable is approximately normally distributed we can make inferences about the values of that variable.

Question 8

The total area under any curve is?

Answer 8

One.

Question 9

Sample size formula:

Answer 9

Z^2
N=—— (s^2)
H^2

Question 10

Sample size formula-proportion:

Answer 10

Z^2
N=——% of pop(1-% of pop)
H^2

Question 11

What is Variance:

Answer 11

How dispersed the data is.

Question 12

What is a synonym for average and how do you find it?

Answer 12

Mean; add all the values and divide by the number of observations.

Question 13

What is a cross tabulation?

Answer 13

A statistical process that summarizes categorical data to create a contingency table.

Question 14

Assuming there is no relationships between variables is called what?

Answer 14

The null hypothesis.

Question 15

How do we find the expected value per cell?

Answer 15

(Column X Row) / Total

Question 16

What does a chi-square test measure?

Answer 16

How much variation there is in each cell of the table.

Question 17

Chi-Square:

Answer 17

(Obs-Exp)^2/Exp

Question 18

How do you calculate the degrees of freedom?

Answer 18

(# of rows -1) x (# of columns -1)

Question 19

Decision Rule:

Answer 19

If test statistic> critical value
reject the null
If test star

Question 20

What is a t-test?

Answer 20

Is statistic that checks if two means our reliably different from each other.

Question 21

What are descriptive statistics?

Answer 21

Statistics that describe the data that you have such as the mean but cannot generalize beyond that.

Question 22

What are inferential statistics?

Answer 22

Statistics like t-test for chi-squared test that allow us to make inferences about the population beyond our data.

Question 23

How does a t-test work?

Answer 23

It is the variance between the groups divided by the variance within the groups.

Question 24

What is a P value?

Answer 24

The P value is the probability that the pattern of the data could be produced by chance that is random data.

Question 25

What is a good guideline to have between four sample size data points?

Answer 25

20 and 30+ data points in each group.

Question 26

What types of t-test are there?

Answer 26

Independent samples, paired samples, and one sample.

Question 27

Independent samples test what?

Answer 27

They compare the means of two different groups.

Question 28

What do you paired sample t-test test?

Answer 28

They compare the means of one group twice before and after.

Question 29

What does a one sample t-test test?

Answer 29

The mean of one group against some other value example IQ.

Question 30

What are the limitations of t-tests?

Answer 30

1. The results of inferential statistics can only be applied to populations that resembled the sample that was tested. 2. Your sample and population should be roughly normal in their distribution though the test is robust.

Question 31

What are the last two limitations of t-tests?

Answer 31

3. You should have roughly similar sized groups. | 4. All data should be independent.

Question 32

The alternative hypothesis states:

Answer 32

There is an association between variables.

Question 33

What is the significance level associated with the 95% confidence interval?

Answer 33

The .05 significance level.

Question 34

The Dependant variable in any test is?

Answer 34

What is changing and can be measured.

Question 35

Null hypothesis in symbols:

Answer 35

Ho: u(before)-u(after) = 0

Question 36

How can you tell whether there was a change in variables or not if you're jump printout was not readable?

Answer 36

If there is a zero between the upper 95% in the lower 95%.

Question 37

Histograms allow us to examine?

Answer 37

The DISTRIBUTION of a variable.