Statistics For Psychology

Front 1

descriptive stats

Back 1

summarizes a group of scores (mean, range, etc.)

Front 2

inferential stats

Back 2

draw conclusions about something (t-test, correlations)

Front 3

population

Back 3

all possible observations (US citizens, MSU students)

Front 4

sample

Back 4

a set of observations from a population (300 MSU students)

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parameter

Back 5

statistical info about a population

Front 6

statistic

Back 6

information about a sample

Front 7

2 variable types

Back 7

discrete and continuous

Front 8

discrete

Back 8

-nominal and ordinal

Front 9

continuous

Back 9

scale variables

-interval and ratio

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nominal

Back 10

qualitative - implies no rank/distance -

EX. eye color, ID#

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ordinal

Back 11

qualitative or quantitative - rank order but can not tell distance between -

EX. getting 1st, 2nd, 3rd in a race w/o times

Front 12

interval

Back 12

quantitative - rank order and distance between ranks

Front 13

ratio

Back 13

quantitative - rank order, distance between ranks, and has a discrete zero point

Front 14

independent variable (IV)

Back 14

variable we manipulate

Front 15

dependent variable (DV)

Back 15

variable observed for chance bc of IV

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confound

Back 16

any variable that could be cause the effect other than the IV

Front 17

reliability

Back 17

consistency

Front 18

valitidy

Back 18

measurement accuracy

Front 19

hypothesis testing

Back 19

drawing conclusions about whether a relationship is supported by evidence

Front 20

operational definition

Back 20

procedures used to measure/manipulate variables

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within-groups

Back 21

all participants experience each level of the IV

Front 22

between-groups

Back 22

each participant experiences only one level of the IV

Front 23

describing distributions

Back 23

modality - kurtosis - skewness - description(describe the mean, mode, range)

Front 24

unimodal

Back 24

1 peak - like normal curve

Front 25

bimodal

Back 25

2 peaks

Front 26

multimodal

Back 26

3+ peaks

Front 27

positive skew

Back 27

tail is pulled to the positive side (right)

Front 28

negative skew

Back 28

tail is pulled to the negative side (left)

Front 29

kurtosis

Back 29

leptokurtic - platykurtic - mesokurtic

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leptukurtic

Back 30

peaked "thin/pointy" distribution

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platykurtic

Back 31

flat "plateau-like" distribution

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mesokurtic

Back 32

normal curve - neither leptokurtic nor platykurtic

Front 33

central tendency

Back 33

descriptive statistics that best represent the center of a data set

Front 34

symmetrical normal distribution

Back 34

mean = median = mode

Front 35

positively skewed distribution

Back 35

mean > median > mode

Front 36

negatively skewed distribution

Back 36

mean < median < mode

Front 37

variability

Back 37

how spread out the data is

Front 38

deviation scores

Back 38

D - the amount a score differs from the mean

Front 39

sum of squares

Back 39

SS - solves the summing deviation scores issue

SS= ∑(x-M)^2

Front 40

average

Back 40

s^2 - usual squared distance from the mean

Front 41

variance of a sample

Back 41

s^2= ∑(x-M)^2

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N-1

Front 42

variance of a population

Back 42

σ^2= ∑(x-M)^2

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N

Front 43

standard deviation of a sample

Back 43

s= √∑(x-M)^2

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N-1

Front 44

standard deviation of a population

Back 44

σ= √∑(x-M)^2

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N

Front 45

random sampling

Back 45

a note on random

Front 46

convenience sampling

Back 46

using readily available participants

EX. most universities use this

Front 47

volunteer sample

Back 47

a type of convenience sampling - aka "self-selected" sample - can be very biased

Front 48

confirmation bias

Back 48

pay attention to information that confirms our initial beliefs

Front 49

illusory correlation

Back 49

believing an association exists when it does not

Front 50

personal probability

Back 50

our own belief of the likelihood an event will occur - not how we think of it in statistics

Front 51

probability definition

Back 51

the actual likelihood an outcome will occur out of all outcomes

success

probability = -----------------

trials

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percentage

Back 52

100x a proportion

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proportion

Back 53

a proportion - always ranges from .00 to 1.00

Front 54

independent trials

Back 54

getting a result cannot effect the outcome of previous trials

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hypothesis

Back 55

a statement that there is a difference between populations or sometimes, more specifically, that there is a difference in a certain direction - a guess as to what you think might be true

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research question

Back 56

an observation, idea, or inquiry about a specific concern or issue

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research hypothesis (H0 / H1)

Back 57

always think in terms of null - we only "reject" or "fail to reject" the null

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the null hypotheses (H0)

Back 58

there is no relationship between the IV and DV

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the alternative hypothesis (H1)

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there IS a relationship between the IV and DV

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non-directional hypothesis

Back 60

H0 = acupuncture does not affect pain tolerance

H1 =acupuncture affects pain tolerance

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directional hypothesis

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H0 =acupuncture does not affect or decrease pain tolerance

H1 =acupuncture increases pain tolerance

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p value

Back 62

the probability that the numerical results we observed were due to chance alone

EX. p= .045 ... there is a .045 probability/4.5% chance that these results are due to chance

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a value

Back 63

alpha - simply a decision criteria - usually set to a=.05

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reject the null when...

Back 64

p < a

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type 1 error

Back 65

we reject the null but the null was true - alpha reduces this

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type 2 error

Back 66

we fail to reject the null, but the null was false - beta value can reduce this

Front 67

hypothesis testing (reference picture)

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