Psych Exam 4 Class Slide Questions Flashcards by Madison Bechard

What is a correlation?

Relationship between 2 variables (x and y)

How well did you know this?

Not at all

Perfectly

What are the two pieces of information that correlations provide?

Magnitude and direction

How well did you know this?

Not at all

Perfectly

What is magnitude?

Degree of relationship between two variables

How well did you know this?

Not at all

Perfectly

What is direction?

How the variables are related

How well did you know this?

Not at all

Perfectly

What is a positive direction?

As x increases y also increases

How well did you know this?

Not at all

Perfectly

What does a negative direction indicate?

As x increases y tends to decrease

How well did you know this?

Not at all

Perfectly

What do correlation coefficients assume?

Linear relationships

How well did you know this?

Not at all

Perfectly

What is a linear relationship?

Relation represented by a straight line

How well did you know this?

Not at all

Perfectly

What do scatterplots graph?

Two variable distribution by placing dots at the value of paired scores

How well did you know this?

Not at all

Perfectly

What does the pattern point reveal in a scatterplot?

Direction of the correlation

How well did you know this?

Not at all

Perfectly

How is magnitude determined?

How closely data points hug the hug line

How well did you know this?

Not at all

Perfectly

What happens with a stronger relationship?

The closer the data points will be to the line

How well did you know this?

Not at all

Perfectly

What happens with the variables if there is no correlation?

Value of one variable doesn’t predict value of other variable

How well did you know this?

Not at all

Perfectly

What is Pearson’s r?

Single statistic indicating direction and strength of correlation

How well did you know this?

Not at all

Perfectly

What does Pearson’s r require?

Multiplying deviations from mean X by mean of Y (cross products)

How well did you know this?

Not at all

Perfectly

What is the second step in finding Pearsons r?

Divide by standard deviations and number of pairs

How well did you know this?

Not at all

Perfectly

What is the equation for Pearsons r?

r= E (X-X-)(Y-Y-)/ noXoY

How well did you know this?

Not at all

Perfectly

What is the value of a perfect positive correlation?

r= +1

How well did you know this?

Not at all

Perfectly

What is the value of a perfect negative correlation?

r= -1

How well did you know this?

Not at all

Perfectly

What is the value of no correlation?

r= 0

How well did you know this?

Not at all

Perfectly

What is a small, moderate, and large correlation strength value?

r=.1 (small), r=.3 (m), r=.5 (l)

How well did you know this?

Not at all

Perfectly

What do strong correlations not provide?

Causation

How well did you know this?

Not at all

Perfectly

What do non-linear effects do to Pearsons r?

Make it look small

How well did you know this?

Not at all

Perfectly

What reduces the effects of Pearsons r?

Restriction of range/talent

How well did you know this?

Not at all

Perfectly

What artificially increases the size of Pearsons r?

Discontinuous distributions

What happens to correlations as sample size increases?

They become more accurate

What are correlations determined by?

Specific measures representing the variables/conditions of measurement

What Is the first issue with hypothesis testing?

Nulls are point estimates almost always false

What is the second issue with hypothesis testing?

No "grey area" between significance and non-significance

What does failing to reject the null provide?

Little info for conclusions

What are confidence intervals?

Interval estimates

What do confidence intervals represent?

Range of values where we are likely to find pop value

What is the first reason to use confidence intervals?

Evidence on likely range of possible values of parameters

What do CI's provide a clear indication of?

How sample size influences accuracy of guessing

What is the second reason to use a confidence interval?

Tool for determining importance of result

What is the basic structure of a confidence interval?

CI= Sample mean +- Margin of error

What do we decide in confidence intervals?

The range we want

What does the range of a confidence interval determine?

Z or T scores we will use

What does a larger interval include?

Larger range of values

What is a higher confidence coefficient?

Confidence pop value falls within boundary

What is the equation for confidence intervals for single means when O^2x is known?

C = X- (+-) z(ox-)

What does a 95% CI mean?

95% confident that what we want falls between the two values

What does a confidence interval of 95% not mean?

Probability of ux being in interval is 95% (its either there or it isn't)

What does a confidence interval of 95% spelled out mean?

Based on ways intervals are constructed 95% will contain uX

What equation do you use when o^2x is not known?

X- (+-) tp (sX-)

What is tp?

t value with prob p of obtaining a value so deviant (determined by interval width)

What is the formula for independent samples t-test?

C= (X-(-) Y-) (+-) tpSX-(-)Y-

What is regression?

Use correlations to determine strength and direction of X and Y relationship

What do we use a regression line to predict?

Person's score on Y (Y') based on x score

What does the regression line give?

Predicted Y value (Y') for every value of X (we regress Y onto X)

What happens when r=0?

z' y will always be zero, Y' will always be the mean of Y

What does the line of best fit minimize?

Distance between itself and observed values of Y

What is Pearsons least squares criterion?

Sum of squared deviations from line is minimized

What does Pearsons least squares criterion have the same idea as?

Sum of squares being minimized around mean (Y' is the mean this time)

What does all of these things in regression assume?

Linear relation, normal distribution of Y, variability of Y around Y' must be same for value of X

What term has this definition: variability of Y around Y' must be same for value of X

Homoscedasticity

What is the equation for standard error of the estimate of Y on X?

Syx= Square root of E (Y-Y')^2 divided by n

What is a useful alternative form of Syx?

Syx = Sy square root 1-r^2

What is the symbol r^2?

Variability Y can be explained by X (coefficient of determination)

What does b mean?

Unstandardized regression coefficient

What does B mean?

Standardized regression coefficient

What is the coefficient of determination?

Proportion of variability in Y related to X

What is the coefficient of non-determination (k^2)?

Proportion of variability Y not related to X

r^2 and k^2 are just proportions of what?

S^2y

What is regression towards the mean?

Any time r<1 value of z'y will be less extreme than zx

What does regression toward the mean not predict?

Values will all end up at the mean of Y over time

What does regression towards the mean not imply?

That you can get extreme scores on x and y (less likely when correlation isn't perfect)

What happens in post-test only?

Designs measure the DV after IV is administered

What is a dependent samples design?

Measurements in one sample are related to measurements in other samples

What are the statistical assumptions for independent samples?

Random sampling, sampling w/ replacement, normal distribution, homogeneity of variance

What are the statistical assumptions of correlated samples?

Random sampling, sampling w/replacement, normal distribution

What is the equation for degrees of freedom in independent samples?

(nx-1) + (ny-1)

What is the equation for df in correlated samples?

n-1 (pairs we have in sample is n)`

What is a repeated measures design?

Same participants measured under two or more conditions, each subject his or her own control

In a within-subjects design what do repeated measures designs expose?

Participants to all levels of Iv

What do matched groups designs do to participants before random assignment?

Rank them

What are matched pairs designs?

Participants naturally paired based on a characteristic

What could you also calculate the dependent t using?

Difference scores D (X-Y)

What do you calculate for every pair in the sample?

Difference between X and Y scores

For this look at the alternative T formulas please

For correlated samples what is the new way to measure hypothesis?

u= 0

What are the advantages of dependent sample t-tests?

Fewer participants, eliminates difference possibilities between levels of IV due to individual differences

What are the disadvantages or dependent samples t-tests?

Sequence and order effects

What are sequence and order effects?

Order participants are exposed to IV levels influences performance

What are independent samples power considerations?

Alpha, effect size, sample size, pop SD, relative n of X and Y samples

What are the correlated samples power considerations?

Alpha, effect size, sample size, pop SD, correlation of X and Y