Exam 1

Question 1

Statistics

Answer 1

collect, analyze, and organize numbers, inference from sampling

Question 2

uncertainty

Answer 2

how sure we are of our answer

Question 3

margin of error

Answer 3

used to talk about uncertainty

Question 4

variables

Answer 4

items represented by letters or symbols

Question 5

quantitative variables

Answer 5

all entries are numerical values (height, weight, etc)

Question 6

categorical variables

Answer 6

names or categories (eye color, car type, gender, etc)

Question 7

predictor

Answer 7

use one or more variables to predict or explain a change in another variable (cause, X: x1, x2)

Question 8

response

Answer 8

what variable is predicted (effect, y)

Question 9

observation

Answer 9

the person or thing the variables are measured on

Question 10

observational study

Answer 10

values are observed, researcher doesn’t manipulate anything

Question 11

Experimental study

Answer 11

researchers assign members to experimental conditions

Question 12

population

Answer 12

entire overall group we are interested in

Question 13

samples

Answer 13

data, subgroup from the population

Question 14

census

Answer 14

whole population statistics

Question 15

parameter

Answer 15

a numeric characteristic pertaining to a population, never know true value, estimation, denoted with greek letter

Question 16

statistic

Answer 16

any number you calculate using data, often used to estimate parameters from a known sample, denote with english letters

Question 17

statistical inference

Answer 17

generalize from a sample to a population - use statistic to estimate value of a parameter

Question 18

relative frequency

Answer 18

categorical data, observations of interest/total observations, always value between 0 and 1

Question 19

location

Answer 19

where data is located on number line

Question 20

mean

Answer 20

average, identifies statistics center

Question 21

median

Answer 21

middle data points (average middle if even number of points)

Question 22

Quartiles

Answer 22

breaks data set into four equal sections

Question 23

Q1

Answer 23

lower quartile, 25%

Question 24

Q3

Answer 24

upper quartile, 75%

Question 25

extremes

Answer 25

minimum and maximum of data set

Question 26

5 number summary

Answer 26

minimum, q1, median, q3, maximum (listed in order)

Question 27

range

Answer 27

maximum - minimum

Question 28

inner quartile range

Answer 28

Q3 - Q1

Question 29

variance

Answer 29

S^2, average sum of squares

Question 30

Sum of squares

Answer 30

distance between each data point and the mean, squared

Question 31

deviation

Answer 31

difference between one observation and the mean

Question 32

standard deviation

Answer 32

s, square root of the variance, standard amount observations vary from the mean

Question 33

categorical data visualization

Answer 33

bar chart and pie chart

Question 34

distribution

Answer 34

frequency with which values are taken on

Question 35

histogram

Answer 35

distribution of a quantitative variable - bar represents number of observations that fall into an interval

Question 36

outliers

Answer 36

data points located far away from the majority of the data

Question 37

box plot

Answer 37

determine shape of distribution, visual representation of five number summary

Question 38

right skewed / positive skewed distribution

Answer 38

lots of small values, mean greater than median

Question 39

left skewed / negatively skewed distribution

Answer 39

lots of large values, mean less than median

Question 40

symmetrical / no skew distribution

Answer 40

roughly mirror image, bell curve

Question 41

Uniform distribution

Answer 41

every bar has roughly the same height, mean and median approximately equal

Question 42

bias

Answer 42

occurs when a study is set up in a way that results will be systematically wrong instead of just by random chance

Question 43

sampling bias

Answer 43

when sample is take in a way we expect it to differ systematically from the population of interest

Question 44

seld-selection bias

Answer 44

occurs when individuals choose if they want to be in the sample or not

Question 45

non-response bias

Answer 45

occurs when certain types of respondents are less likely to answer a survey and reason is related to variable being studied

Question 46

simple random sample

Answer 46

to mitigate bias, samples should be collected randomly (every unit has equal opportunity to be selected)

Question 47

confounding variable

Answer 47

influences both predictor and response variables, but is not accounted for in the study

Question 48

establishing causation

Answer 48

association does not imply causation, causation can only be inferred from a randomized experiment

Question 49

random events

Answer 49

events that are unpredictable

Question 50

probability

Answer 50

a way of quantifying the chance some random event occurs (proportion between 1 and 0)

Question 51

plausibility

Answer 51

reflects a state of knowledge / information / uncertainty

Question 52

relative frequency

Answer 52

if this event was repeated over and over and over again, how often would this outcome occur

Question 53

probability notation

Answer 53

p(x) is the probability that event x occurs, p(x) and p(not x) must sum to 1

Question 54

conditional probability

Answer 54

probability of certain events occurring given that some other event occurs or has occurred - condition is after vertical bar, only focus on things related to condition

Question 55

relationship

Answer 55

use conditional variables to check if two variables are related - check p(a|1) vs p(a|2), if large difference there is a relationship - response variable | predictor variable

Question 56

simpson's paradox

Answer 56

occurs when trend in data reverses when the data is broken down into subgroups

Question 57

percent change

Answer 57

(new-old) / old x 100

Question 58

change in percentage points

Answer 58

new-old

Question 59

z score

Answer 59

how many standard deviations a number is from the mean - positive: above the mean - negative: below the mean - closer to 0: more likely to occur

Question 60

empirical rule

Answer 60

68/95/99.7 how many data points lie within 1,2,3 standard deviations of the mean

Question 61

percentiles

Answer 61

the value of a variable for which the given percentage of values fall below it

Question 62

equivalent

Answer 62

2 values have the same Z score