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NHST & Correlation and Regression
Non-experimental research methods
77
Psychology
Undergraduate 3
02/27/2012

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Cards

Term
What are the 5 steps of the literature review process?
Definition
Step 1. Develop a focused research
question based on an area of interest
Step 2. Develop a list of keywords and
construct a search strategy
Step 3. Choose an appropriate database
Step 4. Conduct your search
Step 5. Evaluate results
Term
What does significance at p < .05 mean?
Definition
The probability of the data given the null hypothesis is < .05
Term
Is this statement correct?
The probability of the data given the null hypothesis is < .05
Definition
Yes
Term
Is this statement correct?
The probability that the null hypothesis is true is < .05
Definition
no
Term
Is this statement correct?
The probability that a Type I error was made just in rejecting H0 is
< .05
Definition
no
Term
Is this statement correct?
The probability that the same result will be found in a replication
study is > .95
Definition
no
Term
Is this statement correct?
The probability that the result is due to chance is < .05
Definition
no
Term
the Bigger your correlation and sample size the ________ the t value is likely to be
Definition
bigger
Term
What does a p value tell you?
Definition
Given that the null is true, what is the probability of these (or more extreme) data occurring.
Term
What other statistics can be used other than p values?
Definition
Effect sizes, confidence intervals
Term
why might p values be low?
Definition
either large sample sizes or large effect sizes
Term
a small effect can be statistically
significant in a ______ sample
Definition
large
Term
a large effect can fail to be statistically significant in a ________ sample
Definition
small
Term
What is a Type I error?
Definition
rejecting the null hypothesis when the null is true
Term
What is a Type II error?
Definition
failing to reject null hypothesis when the null is false
Term
The likelihood of finding significance is proportionate to the __________.
Definition
effect size (the size of the difference you are looking to detect)
Term
When your effect size is large (a big underlying difference) you need ________ people to detect a difference
Definition
less
Term
When can a small effect be statistically significant?
Definition
In a large sample
Term
When can a large effect be statistically insignificant?
Definition
In a small sample
Term
What is power?
Definition
the probability of getting a statistically significant result when there is a real effect in the population. In other words, when the null hypothesis is false.
Term
What can power range from?
Definition
0-1
Term
What do Higher power values indicate?
Definition
high power, higher probability of
finding an effect.
Term
What are the factors that affect power?
Definition
–Study design (stronger manipulations have more
of an effect)
–Level of statistical significance (this can be set to
levels other than .05 ahead of time)
–Type of statistical analysis used
–Measurement error
–Sample size
–The actual magnitude of the effect (effect size)
Term
What is the null hypothesis?
Definition
The null hypothesis states that the
experimental group and the control group are not different with respect to [a specified property of interest] and that any difference found between their means is due to sampling fluctuation
Term
What is The “Crud Factor”
Definition
Almost all of the variables that we measure are correlated to some extent
Term
What is the Inverse probability error
Definition
This error states that p = likelihood that the null hypothesis is true
Term
What is the Odds against chance fallacy
Definition
This error states that p is the probability that the results happened due to chance
Term
What is the Type I error fallacy
Definition
This error states that If p < .05 then the probability that you are wrong in rejecting the null is less than 5%
Term
What is the Replication fallacy
Definition
This error states that p is the probability of finding the same result in another study. If p < .05 the probability of finding the same results in another study is 95%
Term
What is the Magnitude Fallacy
Definition
This error states that p value is an index of the magnitude of an effect
Term
What is the Meaningfulness (causality fallacy) fallacy
Definition
This error states that Rejection of null hypothesis confirms the research hypothesis behind it
Term
What is the Success/Failures fallacy
Definition
This error states that rejection = success, and failure to reject = failure
Term
What is the Zero (equivalence) Fallacy
Definition
This error states that Failure to reject the null means that the effect is zero
Term
What is the Sanctification fallacy
Definition
This error states that thinking that there is a big distinction between .049 .06, .056, .05.

You need to remember that with p values we are dichotomizing a continuum
Term
What is the Reification fallacy
Definition
This error states that Replication success is determined by examining p values. Failure to replicate is evidenced when an effect is significant in one study but not in another.
Term
The null is always assumed to be _____
Definition
true
Term
_____ refers to the probability of the data
Definition
p
Term
A standardized variable has been transformed so that its mean is __ and standard deviation is __
Definition
mean is 0 and standard deviation is 1
Term
A covariance is an example of an _____ estimate.

a) unstandardized
b) standardized
Definition
unstandardized
Term
What does a pearson correlation estimate?
Definition
the degree of linear association between two continuous variables
Term
what does Multiple correlation squared, R2 tell us?
Definition
the proportion of variance in Y that is accounted for by using X1 and X2 simultaneously
Term
What is the range of pearson r correlation?
Definition
-1 to 1
Term
what does r squared indicate?
Definition
the proportion of variance that is explained by x
Term
Why is range -1 to 1 theoretical for pearson correlation r?
Definition
Range could be restricted due to different factors/conditions.
Term
If the relation between X and Y is nonlinear does it affect rxy (correlation)?
Definition
yes
Term
If The variance of either variable is narrow (restricted) does it affect rxy (correlation)?
Definition
yes
Term
If The shapes of the frequency distribution are different (e.g., one is positively skewed and the other negatively skewed) does it affect rxy (correlation)?
Definition
yes
Term
If The reliability of X or Y scores are low does it affect rxy (correlation)?
Definition
yes
Term
Do The means of X and Y affect rxy (correlation)?
Definition
no
Term
If a constant increase of 10 was added to X would it affect correlation?
Definition
no
Term
What are the assumptions of pearson correlation r?
Definition
• Residuals are defined as having a mean of 0
• Are independent
• Normally distributed (aka homoscedasticity)
Term
What is partial correlation?
Definition
The technique of a partial correlation takes a third variable into account
Term
What is spuriousness?
Definition
If the observed relation between X and Y is due to one or more common causes the association between X and Y is said to be spurious
Term
The relation between shoe size
and vocabulary among children is .50; however, this isn’t surprising because they are both caused by a third variable: age. What is this third variable called?
Definition
spurious
Term
what does "controlling for w" do
Definition
removes the effect of a third variable W from both X and Y and reestimates their association
Term
What do part correlations and semi
partial correlations do?
Definition
they partial out the effect of external variables from either Y or X
Term
what does regression analysis do?
Definition
fits a straight line through such a distribution
Term
What does this equation refer to?

Y = B0 + B1X + E
Definition
observed value of Y
Term
What does B1 refer to in this equation?

Y = B0 + B1X + E
Definition
slope, It tells us how much of a change in Y is associated with a one-unit change in X
Term
What does E refer to in this equation?

Y = B0 + B1X + E
Definition
The error variable is a hypothetical variable representing all aspects of Y that are not predicted by X
Term
What does a slope of 2.3 mean?
Definition
it means that a one-unit change in X is associated with 2.3 units of change in Y
Term
Is this equation standardized or unstandardized?
Y = B0 + B1X + E
Definition
unstandardized
Term
Is this equation standardized or unstandardized?
Y = ß0 + ß1X + E
Definition
standardized
Term
The more scatter of data points there is, the _____ the explanation.
Definition
worse
Term
What is multiple regression?
Definition
a regression with more than one
predictor
Term
In this equation, what is B1?
Y = B0 + B1X1 + B2X2 + E
Definition
B1 is the effect of X1 on Y controlling for X2
Term
In this equation
Y = B0 + B1X1 + B2X2 + E
if B1 were equal to 1.6 what would
it mean?
Definition
it would mean that one unit change in X1 is associated with a 1.6 unit change in Y, holding X2 constant.
Term
What does multiple correlation, R tell us?
Definition
R tells us how well the optimally weighted sum of the predictors (X and X) explains Y
Term
Where does the value of R lie between?
Definition
between 0 and 1
Term
What does Multiple correlation squared, R2 tell us?
Definition
R2 tells us the proportion of variance in Y that is accounted for by using X1 and X2 simultaneously
Term
How can R can be tested for statistical significance
Definition
this is done with an F statistic
Term
In a multiple regression, how are the individual B or Betas tested for statistical significance?
Definition
t-test
Term
what does R squared = .633 mean?
Definition
tells us that X accounted for 63% of the variance in Y
Term
What is a categorical predictor?
Definition
Participants either belong to one group or the other. Example: We code females with the number 0 and males with the number 1
Term
When a regression is run with a dummy coded variable, what is the B of the dummy coded variable testing
Definition
the B of the dummy coded variable is testing the mean difference between groups
Term
What is the term for when the two (beta and bivariate correlations) have different signs
Definition
suppression
Term
What is suppression?
Definition
suppression occurs when the
absolute value of a predictor’s beta weight is
greater than its bivariate correlation with the
criterion.
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