Psych Stats Quiz #1 4/3/23

Question 1

descriptive stats

Answer 1

used to summarize and describe a set of data in a clear and convenient fashion usually through numerical values

Question 2

ex of descriptive stats

Answer 2

GPA - summarizes all grades your earned in college

Question 3

inferential stats

Answer 3

because its not practical/realistic/ethical to measure everyone in a population inferential stats draws inferences about a population based upon an observed sample

Question 4

ex of inferential stats

Answer 4

smoker study - studying a subset of smokers to apply observed data to the greater smoking population

Question 5

sample

Answer 5

subset of scores from a population - measure relatively small group of people

Question 6

population

Answer 6

collection of measurements that share a common characteristic, not necessarily people

Question 7

random sample

Answer 7

selected so that every score in the population has an equal chance of being included
ex. sample of smokers for the smoker study

Question 8

variability

Answer 8

people (observations) differ from one another
describes the extent to which scores in a group differ from one another or how spread out or scattered they are

Question 9

reasons for variability

Answer 9

individual differences
unsystematic differences in procedure
research manipulation

Question 10

measurement

Answer 10

the use of a rule to assign a number to a specific observation of a variable
ex. length or weight

Question 11

measurement scale property: category

Answer 11

observations assigned a different number representing the category

Question 12

measurement scale property: ordinal

Answer 12

can be used to measure those with the least amount to the most amount

Question 13

measurement scale property: equal intervals

Answer 13

1 unit difference remains constant

Question 14

measurement scale property: absolute zero

Answer 14

0 represents absence of something

Question 15

type of scale: nominal

Answer 15

categories - qualitative but not quantitative
ex. breed of dog

Question 16

type of scale: ordinal

Answer 16

ranks
ex. class rank = 1 vs 2 vs 3 but doesn’t describe the interval between the ranks

Question 17

type of scale: interval

Answer 17

spacing between intervales is known but there is no absolute zero point
ex. temperature (C or F)

Question 18

type of scale: ratio

Answer 18

spacing between intervals is known and a zero point exists
ex. time and distance

Question 19

frequency distribution

Answer 19

how many times each score value is repeated via table or figure (bar graph)

Question 20

histogram: shape

Answer 20

normal distribution bell curve - most scores cluster in the middle and then extreme scores at the tails
ex. IQ scores

Question 21

histogram: symmetrical distributions

Answer 21

more than one peak - bimodal distribution

Question 22

histogram: skewed distributions

Answer 22

the direction of skew is determined by which direction the tail of the distribution points
if the tail goes in a positive direction = positively skewed and vice versa for neg

Question 23

histogram: central tendency

Answer 23

a typical or representative score value near the center of the distribution

Question 24

variability

Answer 24

how different are the scores from one another

Question 25

variable

Answer 25

a measurement that changes from one observation to the next ex. CESD changes from one smoker to the next

Question 26

constant

Answer 26

measurements that stay the same from one observation to the next ex. boiling point of water

Question 27

measures of central tendency: mean

Answer 27

numerical average, the sum of scores divided by sample size ∑x/n

Question 28

measures of central tendency: median

Answer 28

the score value with half the scores above and below 50th percentile organize from least to greatest and find middle if odd number add together and divide by 2

Question 29

measures of central tendency: mode

Answer 29

the most frequently occurring score can be more than 1 in a given set

Question 30

measures of central tendency: symmetrical distribution

Answer 30

unimodal distribution means that the three scores will be the same spot/number

Question 31

measures of central tendency: skewed distributions

Answer 31

extreme scores have a larger effect on the mean in these cases the median may be better

Question 32

measures of variability: range

Answer 32

largest score minus smallest socre doesn't show the completely different distributions of values very different sets could have the same range

Question 33

measures of central tendency: sample variance

Answer 33

(s²) = sum of squared deviations of each score from the mean divided by n-1 variance determines the deviation around the mean

Question 34

measures of central tendency: sample variance formula

Answer 34

s² = ∑(x - M)²/ n - 1 sum of (all values subtracted from the mean) squared/ divided by the number of cases minus 1

Question 35

measures of central tendency: sample variance steps

Answer 35

1. compute the mean 2. compute each deviation 3. square each deviation 4. sum all the squares (sum of the square deviations from the mean)

Question 36

measures of central tendency: standard deviations (s)

Answer 36

the square root of the variance the measure of how dispersed the data is in relation to the mean low deviation = the data is clustered around the mean high deviation = the data is more spread out

Question 37

validity

Answer 37

how well the measurement rule actually measures the variable under consideration as opposed to some other variable ex. some intelligence test measures actual intelligence rather than being influenced by creativity or memory

Question 38

reliability

Answer 38

an index of how consistently the rule assigns the same number to the same observation ex. an intelligence test is reliable if it assigns the same number to an individual each time they take the text

Question 39

cumulative frequency

Answer 39

the frequency of a score value plus the frequency of all smaller score values ex. Month # cars sold CF January 20 20 February 30 20 + 30 = 50 March 15 50 + 15 = 65 April 18 65 + 18 = 83

Question 40

relative frequency

Answer 40

divide the score value's frequency by the total number of observations in the distribution score value = 3 # of observations = 10 rf = 3/10

Question 41

cumulative relative frequency

Answer 41

tabulation of the relative frequencies of all measurements at or below a given score value

Question 42

class interval

Answer 42

range of score values

Question 43

grouped frequency distribution

Answer 43

tabulation of the number of measurements in each class interval

Question 44

relative frequency histogram

Answer 44

heights of bars represent relative frequencies of score values (or class intervals)

Question 45

population variance

Answer 45

average of the squared deviations of each score from the mean (μ) ex. {3,7,11} sum of the square of distances = 32 32/3 = 10.6

Question 46

population standard deviation (σ)

Answer 46

the positive square root of the population variance