Exam 1

Question 1

Observational Study

Answer 1

observes individuals and measures variables, but doesn’t try to influence the response.

Question 2

purpose of observational study

Answer 2

describe and compare existing groups or situations

Question 3

experiments

Answer 3

actively impose a treatment on the subjects

Question 4

purpose of experiments

Answer 4

study if a treatment causes a change in the response

Question 5

confounding variables

Answer 5

variables thats effects on a response variable can’t be distinguished from each other

Question 6

sample

Answer 6

the part of the population from which the the information is actually collected. samples are used to draw conclusions about the entire population

Question 7

population

Answer 7

the entire group of individuals from which we want the information

Question 8

sampling design

Answer 8

describes how a sample was chosen from the population

Question 9

probability sampling

Answer 9

use chance to select a sample

Question 10

simple random sample (SRS)

Answer 10

basic probability sample- it gives every possible sample of a given size the same chance to be chosen (can be done with software or random digits)

Question 11

systematic random sampling

Answer 11

every __th individual is selected after the starting point

Question 12

stratified random sampling

Answer 12

the population is divided into sub-populations and samples are chosen from each of those

Question 13

multistage random samples

Answer 13

a simple random sample is chosen within a simple random sample (ex: a random classroom within a random school within a random state)

Question 14

bias

Answer 14

systematic errors in the way the sample represents the population/ systematically favors certain outcomes

Question 15

voluntary response samples

Answer 15

individuals can choose to participate. the problem is that mostly people with strong opinions would take the time out to participate

Question 16

convenience sample

Answer 16

the easiest sampling design- the individuals close at hand are selected. the problem is that they cater to specific people (example: all the people are in the same economic class, being an inaccurate representation of the population)

Question 17

sample surveys

Answer 17

observational studies of a random sample drawn from the population

Question 18

cluster sample

Answer 18

populations are divided into groups and entire clusters/ groups are chosen at random to be in the sample

Question 19

unblinded

Answer 19

both the experimenter and the subjects know which treatment is being administered

Question 20

single blind

Answer 20

either the experimenter or the subjects know which treatment is being administered, but not both

Question 21

double blind

Answer 21

neither the experimenter nor the subjects know which treatment is being administered

Question 22

undercoverage bias

Answer 22

when some members of the population are not represented

Question 23

self selection bias

Answer 23

when individuals choose to participate in a survey, leading to a sample with extreme views

Question 24

nonresponse bias

Answer 24

when a significant amount of individuals selected for the sample do not respond, resulting in skewed results

Question 25

response bias

Answer 25

when the way a question is asked influences the answer

Question 26

individuals

Answer 26

the objects described by a set of data

Question 27

variable

Answer 27

describes a characteristic of an individual

Question 28

categorical variable

Answer 28

places an individual in a group or category. they are not numerically valued (qualitative variable)

Question 29

quantitative variable

Answer 29

has numerical value that measure a characteristic of an individual

Question 30

exploratory data analysis

Answer 30

uses graphs and numerical summaries to describe the variables in a data set and the relationships between them

Question 31

discrete variable

Answer 31

type of quantitative variable- it takes on a distinct, countable value. possible values are finite

Question 32

continuous variable

Answer 32

type of quantitative variable- it takes on any value within a range. possible values are infinite

Question 33

distribution

Answer 33

shows how data points are spread across a range and how often they occur

Question 34

graphs for categorical variables

Answer 34

pie charts and bar graphs

Question 35

graphs for quantitative variables

Answer 35

histograms and dot plots

Question 36

bar graphs measure...

Answer 36

any sets of data measured in the same units

Question 37

symmetric shape

Answer 37

clear middle, mirrored sides

Question 38

multimodal

Answer 38

multiple peaks

Question 39

bimodal

Answer 39

2 peaks

Question 40

measures of shape

Answer 40

symmetric, multimodal, bimodal

Question 41

measures of center

Answer 41

median, mean

Question 42

measures of spread

Answer 42

range. standard deviation

Question 43

skewed

Answer 43

the tail is on the side that is skewed

Question 44

outliers

Answer 44

observations that lie outside of the overall pattern of the distribution

Question 45

time plot

Answer 45

plots each observation with the time it was measured. (always have time horizontally)

Question 46

trend (time plot)

Answer 46

a long term upward or downward movement over time

Question 47

cycle (time plot)

Answer 47

a pattern or event that repeats at regular intervals

Question 48

variability

Answer 48

a broad term that describes how spread out the data points are in a dataset

Question 49

standard deviation

Answer 49

a specific measure of variability that quantifies the average distance of each data point from the mean

Question 50

with mean, describe spread using...

Answer 50

standard deviation

Question 51

with median, describe spread using...

Answer 51

5 number summary

Question 52

resistant measure

Answer 52

a statistic that is not significantly affected by extreme values or outliers in a dataset

Question 53

resistant measures examples

Answer 53

median, quartiles, and interquartile range

Question 54

four step method

Answer 54

state, plan, solve, conclude

Question 55

variance=...

Answer 55

square root of standard deviation