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PSYCH 216 > Psych Exam 4 Class Slide Questions > Flashcards

Psych Exam 4 Class Slide Questions Flashcards

1
Q

What is a correlation?

A

Relationship between 2 variables (x and y)

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2
Q

What are the two pieces of information that correlations provide?

A

Magnitude and direction

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3
Q

What is magnitude?

A

Degree of relationship between two variables

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4
Q

What is direction?

A

How the variables are related

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5
Q

What is a positive direction?

A

As x increases y also increases

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6
Q

What does a negative direction indicate?

A

As x increases y tends to decrease

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7
Q

What do correlation coefficients assume?

A

Linear relationships

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8
Q

What is a linear relationship?

A

Relation represented by a straight line

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9
Q

What do scatterplots graph?

A

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

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10
Q

What does the pattern point reveal in a scatterplot?

A

Direction of the correlation

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11
Q

How is magnitude determined?

A

How closely data points hug the hug line

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12
Q

What happens with a stronger relationship?

A

The closer the data points will be to the line

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13
Q

What happens with the variables if there is no correlation?

A

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

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14
Q

What is Pearson’s r?

A

Single statistic indicating direction and strength of correlation

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15
Q

What does Pearson’s r require?

A

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

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16
Q

What is the second step in finding Pearsons r?

A

Divide by standard deviations and number of pairs

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17
Q

What is the equation for Pearsons r?

A

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

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18
Q

What is the value of a perfect positive correlation?

A

r= +1

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19
Q

What is the value of a perfect negative correlation?

A

r= -1

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20
Q

What is the value of no correlation?

A

r= 0

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21
Q

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

A

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

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22
Q

What do strong correlations not provide?

A

Causation

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23
Q

What do non-linear effects do to Pearsons r?

A

Make it look small

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24
Q

What reduces the effects of Pearsons r?

A

Restriction of range/talent

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25
Q

What artificially increases the size of Pearsons r?

A

Discontinuous distributions

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26
Q

What happens to correlations as sample size increases?

A

They become more accurate

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27
Q

What are correlations determined by?

A

Specific measures representing the variables/conditions of measurement

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28
Q

What Is the first issue with hypothesis testing?

A

Nulls are point estimates almost always false

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29
Q

What is the second issue with hypothesis testing?

A

No “grey area” between significance and non-significance

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30
Q

What does failing to reject the null provide?

A

Little info for conclusions

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31
Q

What are confidence intervals?

A

Interval estimates

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32
Q

What do confidence intervals represent?

A

Range of values where we are likely to find pop value

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33
Q

What is the first reason to use confidence intervals?

A

Evidence on likely range of possible values of parameters

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34
Q

What do CI’s provide a clear indication of?

A

How sample size influences accuracy of guessing

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35
Q

What is the second reason to use a confidence interval?

A

Tool for determining importance of result

36
Q

What is the basic structure of a confidence interval?

A

CI= Sample mean +- Margin of error

37
Q

What do we decide in confidence intervals?

A

The range we want

38
Q

What does the range of a confidence interval determine?

A

Z or T scores we will use

39
Q

What does a larger interval include?

A

Larger range of values

40
Q

What is a higher confidence coefficient?

A

Confidence pop value falls within boundary

41
Q

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

A

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

42
Q

What does a 95% CI mean?

A

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

43
Q

What does a confidence interval of 95% not mean?

A

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

44
Q

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

A

Based on ways intervals are constructed 95% will contain uX

45
Q

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

A

X- (+-) tp (sX-)

46
Q

What is tp?

A

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

47
Q

What is the formula for independent samples t-test?

A

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

48
Q

What is regression?

A

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

49
Q

What do we use a regression line to predict?

A

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

50
Q

What does the regression line give?

A

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

51
Q

What happens when r=0?

A

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

52
Q

What does the line of best fit minimize?

A

Distance between itself and observed values of Y

53
Q

What is Pearsons least squares criterion?

A

Sum of squared deviations from line is minimized

54
Q

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

A

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

55
Q

What does all of these things in regression assume?

A

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

56
Q

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

A

Homoscedasticity

57
Q

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

A

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

58
Q

What is a useful alternative form of Syx?

A

Syx = Sy square root 1-r^2

59
Q

What is the symbol r^2?

A

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

60
Q

What does b mean?

A

Unstandardized regression coefficient

61
Q

What does B mean?

A

Standardized regression coefficient

62
Q

What is the coefficient of determination?

A

Proportion of variability in Y related to X

63
Q

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

A

Proportion of variability Y not related to X

64
Q

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

A

S^2y

65
Q

What is regression towards the mean?

A

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

66
Q

What does regression toward the mean not predict?

A

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

67
Q

What does regression towards the mean not imply?

A

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

68
Q

What happens in post-test only?

A

Designs measure the DV after IV is administered

69
Q

What is a dependent samples design?

A

Measurements in one sample are related to measurements in other samples

70
Q

What are the statistical assumptions for independent samples?

A

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

71
Q

What are the statistical assumptions of correlated samples?

A

Random sampling, sampling w/replacement, normal distribution

72
Q

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

A

(nx-1) + (ny-1)

73
Q

What is the equation for df in correlated samples?

A

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

74
Q

What is a repeated measures design?

A

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

75
Q

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

A

Participants to all levels of Iv

76
Q

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

A

Rank them

77
Q

What are matched pairs designs?

A

Participants naturally paired based on a characteristic

78
Q

What could you also calculate the dependent t using?

A

Difference scores D (X-Y)

79
Q

What do you calculate for every pair in the sample?

A

Difference between X and Y scores

80
Q

For this look at the alternative T formulas please

A
81
Q

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

A

u= 0

82
Q

What are the advantages of dependent sample t-tests?

A

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

83
Q

What are the disadvantages or dependent samples t-tests?

A

Sequence and order effects

84
Q

What are sequence and order effects?

A

Order participants are exposed to IV levels influences performance

85
Q

What are independent samples power considerations?

A

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

86
Q

What are the correlated samples power considerations?

A

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

PSYCH 216 (18 decks)

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