Statistics Key REVISION

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What does standard deviation do?
Tell you what the variability of the data is
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What does the standard deviation give you?
It gives you the range of values that contain 68% of the data
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What is the standard error of the mean do?
tells you what range of values the mean might really take
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What does the mean give you the range of ?
Values that would contain 68% of the mean if the experiment was ran several times
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How do you transform data?
Apply a math operation to each individual value
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What are the uses?
How does the brain length relate to intelligence: volume might be better than length itself
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What does it remove?
Non linear effects
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What are Z transforms?
Standardising the data
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How can this be done?
By adding a number to the score, this leads to an increase in the mean but not in the standard deviation
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If the number is multiplied, what does this lead to?
An increase in the mean and STD
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What is the formulation to work out Z score?
Subtract the mean from each score and divide by the standard deviation
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What is the interpretation?
95% will range between -1.96 and +1.96 and 99% will be in range -3 to +3
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What are Z scores?
We know how good/bad a particular score was on a standard scale
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What is a skew?
More common noticeable difference from normal distribution. The size of the tails either side
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What is distribution?
Consider the steps sizes in the measure, distribution of the data is normal
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How do we assess deviation from normal distribution?
Plot a histogram that shows raw data and a normal curve, run a test for normality, how certain are we that data is not normal, normal or interval data
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In hypothesis testing what do we assume?
Our variables are having no effect (H0) unless that seems really unlikely to be true (H1)
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What can we measure?
The probability of seeing our data if there is truly no effect
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If that probability is low then it is improbable that there is no effect therefore what have we found?
There is an effect
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What is alpha set to?
0.05%
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What is H0 and H0?
true negative
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What is H0 and H1?
Type II error
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What is type II error?
Incorrectly accepting the null hypothesis B
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What is H1 and H0?
Type I error
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What is type 1 error?
Incorrectly rejecting the null hypothesis A
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What is H1 and H1?
true positive 1-B probability of finding an effect if there is one
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If H0 were true, what would the peakk be?
On zero
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If H1 was true where would the peak be?
It would be greater than 0
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If the effect was big, then the curve would be more away from what?
0
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What is Bonferroni correction?
If you run many tests in a study then roughly 5% are going to give a false alarm, the simples way to correct this is to reduce your alpha
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HOw?
Divide alpha, your criteria value for P by the number of tests and keep the criteria the same
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Why are Post Hoc tests run?
This is to confirm where the differences occured between groups
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What is regression analysis?
This is useful when you believe you have a relationship between two variables and want to know what the relationship is
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What is a one way ANOVA
One independent variable
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What is a univariate ANOVA?
One dependent variable
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What does ** mean?
Sum of Squares
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What does MS mean?
Mean squares
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Resampling?
Uses all data work out probabilities using stimulations rather than formulas, makes fewer assumptions, two main forms
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What is the first main form?
Randomisation
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What is this?
Shuffle the data and stimulate the null hypothesis, can be used for within and between subject design
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What is boot strapping?
Provides confidence intervals or SEM for individual conditions, therefore be used for one sample test
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What is a partial correlation?
Some times the correlation between two variables is caused by another variable
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What is Variable C referred to as
Partialled out or held constant
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What is a simple correlation called?
A zero order correlation
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What is a first order correlation?
One that partials out a single variable constant
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What is a second order variable?
Two variables are held constant
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Other cards in this set

Card 2

Front

What does the standard deviation give you?

Back

It gives you the range of values that contain 68% of the data

Card 3

Front

What is the standard error of the mean do?

Back

Preview of the front of card 3

Card 4

Front

What does the mean give you the range of ?

Back

Preview of the front of card 4

Card 5

Front

How do you transform data?

Back

Preview of the front of card 5
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