Module 2

Question 1

What is a normal frequency distribution

Answer 1

Mean. median and mode are all in the same

Curve is symmetric around the mean not skewed to one side

Question 2

Negatively Skewed distribution

Answer 2

Mode occurs at the peak
Mean and median pulled to the left
tail to the left

Question 3

Positively skewed distribution

Answer 3

Mode at center of curve

Mean and median are pulled to the right towards more positive numbers

tail to he right

Question 4

Curtosis

Answer 4

leptokurtic points
mesokurtic - normal
platykurtic - flat peak

Question 5

What does an increase in standard deviation do to a distribution or curve

Answer 5

it flattens the curve out or pulls the curve outward

Question 6

Where does 68% of data fall in normal distribution

Answer 6

within + or - 1 standard deviation of the mean

Question 7

Where do 95% of scores occur within a normal distribution

Answer 7

+ or - 2 standard deviations from the mean

Question 8

Where do 99% of data fall within a normal distribution

Answer 8

within + or - 3 standard deviations from the mean

Question 9

What is a z score and how do you calculate it?

Answer 9

compares the mean of a sample with the population mean

Also a way to identify outliers if they are 3 or greater standard deviations

Z = (individual score - mean) / SD

Question 10

How do you perform a hypothesis test

Answer 10

1. Develop a null and research hypothesis
2. Choose a level of significance
3. Determine which statistical test is appropriate
4. Run analysis to obtain test statistic and p value
5. reject or fail to reject the null hypothesis
6. Make a conclusion

Question 11

Hypothesis

Answer 11

statements that predict the relationship between variables

they are testable and translate the research question into a prediction

Question 12

Null hypothesis

Answer 12

There is no relationship

Question 13

Research hypothesis can be two things

Answer 13

directional or non-directional

Question 14

directional vs non-directional

Answer 14

you think something is going to go in one direction
one tailed test
non-directional - you don’t know which direction so you would run a two tailed test

Question 15

Level of significance

Answer 15

How much error you are okay with

percent of time you say there will be a statistical signifcance but there in fact is not
p = 0.05
5% time you make a type I error

can raise or lower if you want to be conservative or not

Question 16

Type I error

Answer 16

probability of concluding that there is a difference in groups when there is not

Question 17

Type II error

Answer 17

probability of concluding that there is no difference between groups or no relationship between variable when there truly is

Probability of accepting a null hypothesis when it is not true

Question 18

What does which statistical test you choose depend on

Answer 18

number of variables
levels of measurement (nominal, ordinal, interval, ratio)
assumptions of statistical test

Question 19

P value

Answer 19

probability that the difference, or one larger, could arise by chance

Probability of seeing this outcome by just chance
to reject null hypothesis your p value needs to be lower that the statistical significance score you set 0.05

Question 20

If calculated p value is bigger than level of significance

Answer 20

fail to reject null hypothesis or ACCEPT

Question 21

calculated p value is smaller than level of significance you set

Answer 21

reject the null hypothesis and accept the research hypothesis

Question 22

T test for independent groups when would you use

Answer 22

When you are comparing the means of two independent groups

Groups have to be unrelated to each other

Question 23

T test for independent groups assumptions

Answer 23

Independence
Normality
Homogeneity of variances
dependent variables must be interval or ratio (comparing means)

Question 24

How do you determine homogeneity of variances?

Answer 24

By doing a Levene’s test for equality of variances

Question 25

What should read out be for Levine’s test for equality of variances be

Answer 25

Sig (p value) should be greater than 0.05
Must use equal variances assumed row in

Question 26

How do you report t test output in SPSS

Answer 26

Question 27

How do you write out T test results

Answer 27