UNIT 4

Question 1

Random Variable

Answer 1

a quantitative variable whose value depends on chance.

Question 2

A _____ _____ describes the outcomes of a

statistical experiment in words

Answer 2

Random Variable

Question 3

Discrete Random Variable/ Probability distribution function

Answer 3

A listing of the possible

values and corresponding probabilities of a discrete random variable, or a formula for the probabilities

Question 4

Probability histogram

Answer 4

A graph of the probability distribution that displays the possible values of a discrete
random variable on the horizontal axis and the probabilities of those values on the vertical axis.

Question 5

A discrete PDF (Probability Distribution Function) has ___ characteristics

Answer 5

two

Question 6

Each probability is between _ and _, inclusive, in other words includes zero and one

Answer 6

0,1

Question 7

PDF Function

Answer 7

𝟎 ≤ 𝑷(𝑿 = 𝒙) ≤ 1

Question 8

Sigma Σ means to

Answer 8

Sum up

Question 9

The sum of all probabilities in a distribution is always _

Answer 9

1

Question 10

equation for the sum of all probabilities

Answer 10

Σ P(X=x)=1

Question 11

Expected Value

Answer 11

is the long-term average or mean. It is the long term mean of doing
an experiment over and over. It is the expected average.

Question 12

Variable

Answer 12

A characteristic that varies from one person or thing to another

Question 13

Qualitative Variable

Answer 13

A non-numerically valued variable; categorical variable (hair color)

Question 14

Quantitative Variable

Answer 14

A numerically valued variable; numerical variable (weight)

Question 15

Discrete Variable:

Answer 15

A quantitative variable whose possible values can be listed. In particular, a quantitative
variable with only a finite number of possible values is a discrete variable.

Question 16

Continuous Variable

Answer 16

A quantitative variable whose possible values form some interval of numbers

Question 17

Data

Answer 17

Values of a variable.

Question 18

Qualitative Data

Answer 18

Values of a qualitative variable.

Question 19

Quantitative Data

Answer 19

Values of a quantitative variable

Question 20

Discrete Data

Answer 20

Values of a discrete variable; result of counting

Question 21

Continuous Data:

Answer 21

Values of a continuous variable; result of measuring

Question 22

The number of books in a backpack is ____, the weight of these books is ____.

Answer 22

discrete; continuous

Question 23

Census

Answer 23

Collects information from the entire population for which data already exist

Question 24

Sampling

Answer 24

Collect information from a representative part of the population.

Question 25

Sampling is done when

Answer 25

it would be impractical to collect data from the entire population

Question 26

Experimentation

Answer 26

data generated by carefully conducting an experiment

Question 27

Simple Random Sampling

Answer 27

A sampling procedure for which each possible sample of a given size is equally likely to be the one obtained

Question 28

Simple Random Sampling With Replacement (SRSWR):

Answer 28

: wherein a member of the population can be | selected more than once

Question 29

Simple Random Sampling Without Replacement (SRS)

Answer 29

wherein a member of the population can be | selected at most once

Question 30

random-number generators

Answer 30

software that generates random numbers

Question 31

. Systematic Random Sampling

Answer 31

Population/Sample Size rounded down = m use a generator to generate a number (k) between 1 and m Select k, k+m k+2m...

Question 32

Clusetr Sampling

Answer 32

Divid pop into groups/clusters obtain random sample from clusters use all members from step 2 as the sample

Question 33

Stratified Random Sampling with Proportional Allocation

Answer 33

Divide Pop unto Strata (subpops) fom each subpop, create a proportional sample size (strata/population= % sample for each strata) all members from step two are the sample

Question 34

Convenience Sampling

Answer 34

A type of non-random sampling, uses results that are readily available; conducting a study related to organic food and collecting data from customers as they walk through the doors of Whole Foods

Question 35

You are conducting a survey of students in a dormitory. You choose your sample by knocking on the door of every 10th room. Choosing every 10th room makes this a ______ ______. The sample may be representative, as long as students were randomly assigned to rooms.

Answer 35

Systematic sample

Question 36

To survey opinions on a proposed new water line, a research firm randomly draws the addresses of 150 homeowners from a public list of all homeowners. The records presumably list all homeowners, so drawing randomly from this list produces a _____ _____ _____. It has a good chance of being representative of the population.

Answer 36

Simple Random sample

Question 37

Agricultural inspectors for Jefferson County check the levels of residue from three common pesticides on 25 ears of corn from each of the 104 cornproducing farms in the county. Each farm may have different pesticide use, so the inspectors consider corn from each farm as a subgroup (stratum) of the full population. By checking 25 ears of corn from each of the 104 farms, the inspectors are using _____ _____. If the ears are collected randomly on each farm, each set of 25 is likely to be representative of its farm.

Answer 37

Stratified sampling

Question 38

Anthropologists determine the average brain size of early Neanderthals in Europe by studying skulls found at three sites in southern Europe. By studying skulls found at selected sites, the anthropologists are using a _______ _____. They have little choice, because only a few skulls remain from the many Neanderthals who once lived in Europe. However, it seems reasonable to assume that these skulls are representative of the larger population.

Answer 38

Convenience sample

Question 39

Sampling Bias

Answer 39

occurs when a sample is collected from a population and some members of the population are not as likely to be chosen as others

Question 40

Sampling bias can lead to

Answer 40

incorrect conclusions being drawn about the population being | studied

Question 41

Sampling Errors

Answer 41

are those that occur in the actual sampling process; such as the sample not being large enough

Question 42

Non-Sampling Errors

Answer 42

are tied to factors not related to the sampling process such a defective counting device

Question 43

A sample can ____ __ an exact representative of the population (unless the sample is exactly equal to the population) so there will always be some ____ ____.

Answer 43

never be;sampling error

Question 44

Distribution of a Data Set

Answer 44

is a table, graph, or formula that provides the values of the observations and how often they occur

Question 45

Unimodal

Answer 45

one peak

Question 46

bimodal

Answer 46

two equal peaks

Question 47

multimodal

Answer 47

many equal peaks

Question 48

Symmetrical distributions can be shaped as

Answer 48

bell, triangular, rectangular

Question 49

Skewed Ditributions skew ___ or ___

Answer 49

right or left

Question 50

Reverse J Shaped distribution

Answer 50

swoop down left to right

Question 51

Population Data

Answer 51

The values of a variable for the entire population

Question 52

Sample Data:

Answer 52

The values of a variable for a sample of the population

Question 53

The distribution of population data is called the

Answer 53

Population Distribution, or the distribution of the variable.

Question 54

The distribution of sample data is called a

Answer 54

Sample Distribution

Question 55

Truncated/Non-Truncated Graphs

Answer 55

By truncating the scale on the vertical axis it gives the impression that the differences between the bars are far greater than they really are.

Question 56

Improper Scaling

Answer 56

Number of homes this year will be double last year, so the developer doubled the width and height, which makes it look like four times the number of homes will be built.

Question 57

Random Variable

Answer 57

is a quantitative variable whose value depends on chance

Question 58

describes the outcomes of a | statistical experiment in words

Answer 58

Random Variable

Question 59

Typically, upper case | letters such as X or Y are used to represent

Answer 59

Random Variables

Question 60

Continuous Random Variable

Answer 60

a random variable whose possible values form some interval or range of numbers

Question 61

Continuous Random Variables Represent

Answer 61

values that are measured such as baseball batting averages, IQ scores, the length of time a long-distance phone call lasts, SAT scores,

Question 62

Probability Density Function pdf:

Answer 62

A curve representing the probability distribution of a continuous random variable.

Question 63

function of graphs

Answer 63

f(x)

Question 64

Cumulative Distribution Function cdf:

Answer 64

Area under the curve used to evaluate probabilities

Question 65

The area under the curve is always equal to

Answer 65

1

Question 66

𝑷(𝒄 < 𝑿 < 𝒅) is the probability that

Answer 66

the random Variable (X) falls between values c and d on the x axis

Question 67

Probability is found for ____ of x-values and NOT for _____ x-values

Answer 67

intervals ;individual

Question 68

𝑷(𝑿 = 𝒄) =0

Answer 68

the probability that X equals a specific value is zero

Question 69

Uniform Distribution

Answer 69

a distribution that has constant probability since all events are equally likely to occur

Question 70

Almost all the observations in any data set lie within _____ standard deviations to either side of the mean

Answer 70

three

Question 71

Number of Standard Deviations is more commonly | referred to as the _____

Answer 71

z-score

Question 72

Z Score =

Answer 72

(𝑫𝒂𝒕𝒂 𝑽𝒂𝒍𝒖𝒆 − 𝑴𝒆𝒂𝒏)/ | 𝑺𝒕𝒂𝒏𝒅𝒂𝒓𝒅 𝑫𝒆𝒗𝒊𝒂𝒕𝒊𝒐n

Question 73

μ

Answer 73

mu=mean of population

Question 74

σ

Answer 74

= standard deviation