Exam 1

Question 1

population

Answer 1

everyone and everything that is generalized toward

Question 2

sample

Answer 2

subset of population that is represtatice of population

Question 3

unit of observation

Answer 3

element or case of the population that data is collected from

Question 4

statistic

Answer 4

summary at sample level

Question 5

parameter

Answer 5

summary at population level

Question 6

sampling variability

Answer 6

when every possible sample differs, and the statistics generated will vary

Question 7

nominal, ordinal, discrete and continuous variables

Answer 7

nominal: falls into categories with no inherent order/ scaling
ordinal: has categories with meaningful ordering
discrete: numeric scale with limited values
continuous: numeric and measurable, taken any value in a range

Question 8

barplots

Answer 8

show single categorical variables with groups on x and frequencies/ proportion on y

Question 9

histograms

Answer 9

show a single numeric variable, numeric variable in x and y is count/ observations

Question 10

proportion

Answer 10

number of cases that fit a category of interest divided by total number of cases

Question 11

π

Answer 11

parameter that represents population proportion

Question 12

p hat

Answer 12

statistic that represent sample proportion

Question 13

mean

Answer 13

balancing point of data, the sum of all values divided by sample size

Question 14

µ

Answer 14

parameter representing population mean

Question 15

x bar

Answer 15

statistic representing sample mean

Question 16

median

Answer 16

value in middle of observation

Question 17

range

Answer 17

basic measure of variability, the distance between highest and lowest

Question 18

mean absolute deviation

Answer 18

finds average distance from mean in data

Question 19

varaince

Answer 19

average square distance from the mean (sd)

Question 20

𝛔

Answer 20

parameter for variance, represents population sd

Question 21

s

Answer 21

statistic representing sample sd

Question 22

precentile

Answer 22

used to reference key values in the distribution, quartiles used to describe data

Question 23

barplots

Answer 23

represent 5 number summary of numeric variable, min, max, and middle fences

Question 24

response variable

Answer 24

variable interested in understanding/ predicting (target outcome)

Question 25

explanatory variable

Answer 25

variable that might help predict/ explain response variable

Question 26

stacked barplot

Answer 26

compares 2 categorical values with total count or proportion

Question 27

Pearson's correlation coefficient

Answer 27

compares 2 numeric variables, statistics between -1 and +1 describes direction and strength of linear association of 2 numeric variables

Question 28

null hypothesis

Answer 28

assumes no change, difference or association in the situation, parameter follows status quo

Question 29

null model

Answer 29

positive results that can happen under the null hypothesis

Question 30

p value

Answer 30

probability of compatibility of null hypothesis with sample result

Question 31

directional investigation

Answer 31

results only matter (support theory) if they are lower or higher than expected

Question 32

non direction investigation

Answer 32

results support theory if they deviate in either direction from expectation

Question 33

alternative hypothesis

Answer 33

the parameter is an alternative value, some difference, change, or association

Question 34

hypothesis

Answer 34

statement about a parameter

Question 35

significance level 𝝰

Answer 35

used to determine decision, unusual threshold that has to be passed to determine if null is wrong

Question 36

type I error vs type II error

Answer 36

type 1: false alarm, null hypothesis is incorrectly rejected type II: missed opportunity, incorrectly "fail to reject" when there is a difference

Question 37

estimator

Answer 37

statistic from data that estimates parameter of interest

Question 38

absolute error

Answer 38

distance between specific estimate and parameter

Question 39

population distribution

Answer 39

the entire distribution of a particular variable

Question 40

sample data distribution

Answer 40

distribution of measurements collected from the sample has limited data and an incomplete picture of the population

Question 41

normal distribution

Answer 41

identifiable bell curve and symmetric

Question 42

central limit theorem

Answer 42

even if a variable is not normally distributed, the distribution of x bar will become normally distributed if the sample size generating the sample mean is sufficiently large