Module 2 Flashcards

1
Q

What is a normal frequency distribution

A

Mean. median and mode are all in the same

Curve is symmetric around the mean not skewed to one side

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2
Q

Negatively Skewed distribution

A

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

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3
Q

Positively skewed distribution

A

Mode at center of curve

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

tail to he right

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4
Q

Curtosis

A

leptokurtic points
mesokurtic - normal
platykurtic - flat peak

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5
Q

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

A

it flattens the curve out or pulls the curve outward

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6
Q

Where does 68% of data fall in normal distribution

A

within + or - 1 standard deviation of the mean

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7
Q

Where do 95% of scores occur within a normal distribution

A

+ or - 2 standard deviations from the mean

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8
Q

Where do 99% of data fall within a normal distribution

A

within + or - 3 standard deviations from the mean

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9
Q

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

A

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

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10
Q

How do you perform a hypothesis test

A
  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
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11
Q

Hypothesis

A

statements that predict the relationship between variables

they are testable and translate the research question into a prediction

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12
Q

Null hypothesis

A

There is no relationship

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13
Q

Research hypothesis can be two things

A

directional or non-directional

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14
Q

directional vs non-directional

A

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

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15
Q

Level of significance

A

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

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16
Q

Type I error

A

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

17
Q

Type II error

A

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

18
Q

What does which statistical test you choose depend on

A

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

19
Q

P value

A

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

20
Q

If calculated p value is bigger than level of significance

A

fail to reject null hypothesis or ACCEPT

21
Q

calculated p value is smaller than level of significance you set

A

reject the null hypothesis and accept the research hypothesis

22
Q

T test for independent groups when would you use

A

When you are comparing the means of two independent groups

Groups have to be unrelated to each other

23
Q

T test for independent groups assumptions

A

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

24
Q

How do you determine homogeneity of variances?

A

By doing a Levene’s test for equality of variances

25
What should read out be for Levine's test for equality of variances be
Sig (p value) should be greater than 0.05 Must use equal variances assumed row in
26
How do you report t test output in SPSS
27
How do you write out T test results