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PSYC 2021 > Statistics > Flashcards

Statistics Flashcards

1
Q

What is statistics?

A

A branch of mathematics devoted to the collection, analysis, interpretation, and presentation of data

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2
Q

What is a population?

A

Set of all individuals of interest in a particular study, entire group of interest, usually quite large

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3
Q

What is a sample?

A

Set of individuals selected from a population, subset, purpose is to represent population

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4
Q

What is a measurable quality of a population called? What are they represented by?

A

parameter, greek letters (mu/sigma)

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5
Q

What is a measurable quality of a sample called? What are they represented by?

A

statistic, english letters (m, s)

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6
Q

What does descriptive statistics do?

A

describe and present data using graphs etc

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7
Q

What does inferential statistics do?

A

Generalize from samples to populations, make predictions (t-tests, ANOVA)

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8
Q

What is sampling error?

A

Natural differences that exist, by chance, between a sample statistic and a population parameter

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9
Q

What is the experimental method?

A

goal is to demonstrate a cause-and-effect relationship, involves manipulation/control

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10
Q

What are extraneous variables?

A

variables that are not of interest to the researcher in a particular study but could influence the dependent variable

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11
Q

What are some examples of participant variables?

A

age, gender, education level, IQ

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12
Q

What are some examples of environmental variables?

A

lighting, time of day, and background noise/distraction

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13
Q

What is random assignment?

A

Each participant has an equal chance of being assigned to each of the treatment conditions or groups

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14
Q

What is matching?

A

Used to ensure equivalent groups or equivalent environments

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15
Q

What is holding constant?

A

hold extraneous vairbale constant across all gorups

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16
Q

What are non-experimental methods?

A

no ability to control which participants go in what group

ex. surveys, correlational research, observational research

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17
Q

What is the independent vairbale called in non-experimental studies?

A

qausi-independent variable

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18
Q

What are discrete variables?

A

Separate, indivisible categories, no values between categories (no decimals)
Ex. number of children, number of siblings, number of pets

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19
Q

What are continuous variables?

A

Infinite number of possible values that fall between any two observed values (decimals)
Ex. height, weight, skull circumference etc

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20
Q

What are the four scales of measurment in order of least to most compelx?

A

nominal, ordinal, integral, ratio

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21
Q

WHat is nominal?

A

non-numerical, qualitivative categories
ex. eye colour

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22
Q

What is ordinal?

A

ordered attributes wiht no known differences between values

ex. likert scale, race results, clothing size

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23
Q

What is integral?

A

ordered attributes with known differences but no true 0

ex. temp in C, IQ, SAT score

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24
Q

What is ratio?

A

orderd attributes with knwon differences and true zero

ex. temp in K, height, weight

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25
Q

What are frequency distributions?

A

method to organize/simplify data, can be a table or a graph

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26
Q

What is always included in a freuqneyc distribution?

A

set of cateogires, and the frequency/number of indivuals in that category

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27
Q

What does the sum of frequncies need to equal?

A

N (total number of participants0

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28
Q

How can you calculate propotion? What should they add up to?

A

p=f/N

add up to 1

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29
Q

How can you find the percentage using the proportion?

A

multiply by 100

30
Q

How do you use frequency table to calculate mean?

A

add the number of each participant in each category (so if category=9 has frequnecy of 3, you need to add 9, 3 times)

31
Q

What is a grouped frequency distirbution? Why is it used?

A

column X shows groups of scores (ex. 1-10)

use when set of scores if too large

32
Q

What are pros/cons of grouped frequency disttibution?

A

pro: easier to read/understand

con: some info is lost when categories are grouped

33
Q

When are histograms appropiate? What else would be acceptable?

A

for integral/ratio data

frequency polygon

34
Q

When are bar graphs appropiate?

A

for nomial/ordinal data

35
Q

WHat are the 3 characterisitcs of frequency distributions?

A

shape, central tendency, variability

36
Q

When are distributions said to be skewed?

A

if scores are mostly on one side

37
Q

What does a positive skew look like?

A

most scores are on lower/negative side and the tail tapers towards posititvw

38
Q

What does a negative skew look like?

A

most scores are on higher/positive end and tail tapers towards negative

39
Q

How can you check if data is normally distirbted?

A

can use histograms, numerical descriptives, shaprio-wilk test

40
Q

What is the purpose of measuring central tendency?

A

Find single score that is most typical/representative of entire group

41
Q

What is mean?

A

arithmatic average of set of scores/values

42
Q

If data is perfect what measure of central tendency should we use?

A

mean (strongest method)

43
Q

How adding/subtracting a constant from each score affect the mean?

A

mean changes by same constant

44
Q

What does multiplying/dividing each score by same constant affect mean?

A

mean is multiplied/fivided by wsame constant

45
Q

What is the median?

A

midpoint of the data (from smallest to largest)

46
Q

If you are finding the median what do you do when there are an odd number of scores?

A

add middle 2 scores and didivide by 2

47
Q

What is mode?

A

number that is most frequent

48
Q

What measure of central tendency can you have multiple answers for?

A

mode

49
Q

What definition are we using for mode in this course?

A

strict (only bimodal if both modes have same frequency)

50
Q

When should the median be used over the mean?

A

when there are extreme scores/skewed distribution, undetermined values, open ended distributions, ordinal data

51
Q

When should the mode be used?

A

nominal scale

52
Q

What is mean, median, mode in symettrical unimodal distribution?

A

mean=median=mode

53
Q

What is mean, median, mode in symettrical bimodal distribution?

A

mean=median, but not mode

54
Q

What is relationship of mean, median, mode for positive skew distribution?

A

mode<median<mean

55
Q

What is relationship of mean, median, mode for negative skew distribution?

A

mode>median>mean

56
Q

What is range? What is the equation?

A

Distance covered by scores in distribution forms smallest to largest score

range = Xmax - Xmin

57
Q

Where does summation go in bedmas?

A

after multiply/divide (BEDMSAS)

58
Q

How do you calculate variance for sample?

A

s^2= summation of (x-m)^2/n-1

59
Q

What is variance?

A

average squared distance from the mean

60
Q

How does the variance differ between a sample and a population?

A

samples tend to have less variability

61
Q

How does the variance equation change for a population?

A

denomitaor is just N not (n-1)

62
Q

What does degree of freedom mean?

A

the number of independent variables that can vary in an analysis without breaking any constraints

63
Q

How do you find the standard deviation?

A

take the square root of the variance

64
Q

How does adding/subtracting a constnat from each score change the standard deviation?

A

std will not change, (b/c each score remains at same distance from mean)

65
Q

How does multiplying/dividing a constant from each score change the standard deviation?

A

will multiply/divide std by same constant

66
Q

What do z scores do?

A

locate the location of a score in a distribution

67
Q

What does the sign of a z score tell you?

A

+ means above the mean, - means below the mean

68
Q

What does the mean always equal in z scores? What about std?

A

0, 1

69
Q

WHat is the formula for z score?

A

z= (score - mean)/std

70
Q

What do standarized distirubution look like compared to the original data?

A

graph has same shape, score is in same lcoation just renamed

71
Q

How would you find what the new score would be given the old and new distributions mean and std and the old score?

A

convert old score to z score in old distribution, then plug that z score into X= mean + (z*std), using mean and std of new distribution

PSYC 2021 (2 decks)

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