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PSY 230 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

correlation

A

measures and describes a relationship between two variables

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2
Q

linear vs curvilinear

A

linear: forms a line
curvilinear: has a curve
* to determine do a scatterplot

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3
Q

positive vs negative relationship

A

positive: has an upward slope, direct (when Y increases X increases)
negative: has a downward slop, inverse (when Y increases X decreases)

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4
Q

scatterplot

A

graph used for correlation that graphs all points in a data

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5
Q

correlation coefficient (pearson r)

A

specific measure of a correlation
from -1 to 1

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6
Q

pearson r formula

A

SP/ sqrt SSxSSy

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7
Q

coefficient of determination (r^2)

A

measures the percentage of variability in one variable which is determined by its relationship with the other variable

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8
Q

what is another word for the coefficient of determination?

A

effectsize

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9
Q

what are the ranges of effectsize?

A

small: r=10 -> r2= 1%
mid: r=30 -> r2= 9%
large: r=50 -> r2= 25%

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10
Q

spearman rho (rs)

A

used for ordinary scaling

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11
Q

spearman rho formula

A

rs= 1- (6 sigma D1^2 / N^3 - N)
where:
D1= Rank B - Rank A * sum should equal 0

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12
Q

why does correlation not imply cuasation

A

we are only observing the relationship between the two variables we are not influencing either of them
* there can always be a third variable that is influencing them

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13
Q

pearson r

A

measures the degree of a straight line
- only for interval and ratio scales

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14
Q

define regression

A

regression focuses on using the relationship for the purpose of PREDICTION
- linear relationship between 2 variables
- paired scores

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15
Q

define regression line

A

we can predict a score of one variable (Y) based on our knowledge of the other (X)

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16
Q

Linear regression equation

A

Y’ = byX + ay
where:
by= SP/SSx
ay= Ybar - by(Xbar)

17
Q

regression constant

A

that value where the regression line crosses the y-axis
* ay

18
Q

standard error of estimate

A

tells us how far away, on average, a point will be from the regression line
* for accuracy we want a low value

19
Q

Specify the conditions that must be met to use linear regression

A
  • to determine if the relationship is linear use scatterplot
  • random sampling
  • can only be used to make predictions within the range
  • we are not interested in the individuals who are apart of the group used for linear regression
20
Q

define a random sample

A

each possible sampled of a given size has an equal chance of being selected

21
Q

why is it important to use random sampling?

A

decreases error

22
Q

what are the two ways to conduct random sampling?

A
  1. sampling with replacement
  2. sampling without replacement
23
Q

sampling WITH replacement

A

each member of the population selected is returned
- does not change probability

24
Q

sampling WITHOUT replacement

A

selected member of the population is not returned
- probability WILL change

25
Q

a priori

A

before hand, based on rationalism

26
Q

a posterior

A

after the fact, based on empiricism

27
Q

a priori formula

A

p(A) = # of events classifiable as A / total N of possible events

28
Q

a posterior formula

A

p(A) = # of times A occurred / total N of possible events

29
Q

what are the three basic points in probability?

A
  1. can be defined in two ways: a priori or a posterior
  2. can be a fraction, decimal, or percentage
  3. range is from 0 to 1
30
Q

the addition rule

A

p(A or B) = p(A) + p(B) - p(A and B)
* OR = ADDITION
!! if mutually exclusive: p(A) + p(B)

31
Q

multiplication rule

A

INDEPENDENT: p(A and B) = p(A) x p(B)

DEPENDENT: p(A and B) = p(A) x p(B|A)

Mutually exclusive: p(A and B) = 0

32
Q

mutual exclusive events

A

A and B CANNOT happen at the SAME time; has to be OR

33
Q

independent

A

they do NOT influence each other = sampling with repalcement

34
Q

dependent

A

has an effect of probability = sampling without replacement

35
Q

exhaustive

A

includes all of the possible events

36
Q

when there are only two events…

A

we call that P and Q
- P + Q = 1

37
Q

Define probability in conjunction with a continuous variable

A

when using a continuous variable use z-score

PSY 230 (4 decks)

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