HW1 CH6 - intro to Stats & Sampling

Question 1

Define individuals

Answer 1

the objects described by a set of data that contains information

Question 2

define variables

Answer 2

describes some characteristic of an individual such as a person’s height, sex, or age

Question 3

define categorical variable

Answer 3

Places each individual into a category such as male or female

Question 4

define quantitative variable

Answer 4

has numerical values that measure some characteristic of each individual, such as height in cm or age in years (numerical information)

Question 5

Define ordinal variable

Answer 5

a ranked categorical variable (example: freshman, sophmore, junior, senior)

Question 6

explain exploratory data analysis

Answer 6

uses graphs and numerical summaries to describe the variables in a data set and the relations among them

Question 7

define distribution

Answer 7

describes what values the variable takes and how often it takes these values

Question 8

define frequency distribution

Answer 8

the variable (levels or choices) and how often each choice occurs. Examples are the number of occurrences

Question 9

TEST!!!! define relative frequency

Answer 9

ratio of frequency to the total number of observations in the data set. (the frequency/the total) = relative frequency

Question 10

define relative frequency distribution

Answer 10

a listing of distinct values from the data set and their relative frequencies.

Question 11

define pie charts

Answer 11

displays the distribution of variables of a categorical variable by comparison

Question 12

define bar graphs

Answer 12

A graph drawn using vertical bars. The height of each bar represents the frequency or relative frequency of each category. For categorical data, the bars are kept separate.

Question 13

define histograms

Answer 13

displays the distribution of a quantitative variable

Question 14

define dotplots

Answer 14

displays the distribution of a quantitative variable

Question 15

define outliers

Answer 15

are observations that lie outside the overall pattern of a distribution. always try to explain them

Question 16

define time plot

Answer 16

used when observations on a variable are taken over time that graphs time horizontally and the values of the variable vertically

Question 17

Define population

Answer 17

the entire group of individuals about which we want information

Question 18

define sample

Answer 18

The part of the population from which we collect information. We use this to draw conclusions about the entire population

Question 19

A good sample…

Answer 19

represents the population

Question 20

Use the line from the Table of Random Digits (Table B) shown below to generate 5 random numbers between 01 and 49. The first random number is _____.
14459 26056 31424 80371 65103 62253 22490 61181

Answer 20

14

Question 21

If people tend to respond differently to a question depending on whether the questioner is male or female, which type of bias is present?

Answer 21

Response Bias

Question 22

A study that contacts participants at regular time intervals to collect relevant information about events that occur after the start of the study is called a __________ study.

Answer 22

Prospective

Question 23

What type of study can be used to provide the most convincing evidence of cause and effect?

Answer 23

An experiment

Question 24

Determine whether the data set is a population or a sample.
All male students at Lincoln High School.

Answer 24

Population because it is a collection of all male students

Question 25

You would like to select an SRS of 5 packages of peanuts from a case containing 30 packages of peanuts. You begin by labeling the packages 01 to 30. A line from a table of random digits is shown below. 14459 26056 31424 80371 65103 62253 22490 61181 If the line above is used to select the sample, what will be the label numbers for the five packages of peanuts in the random sample?

Answer 25

14, 03, 10, 22, 06

Question 26

A Gallup poll sponsored by the disposable diaper industry asked, "It is estimated that disposable diapers account for less than 2% of the trash in today's landfills. In contrast, beverage containers, third-class mail and yard waste are estimated to account for about 21% of the trash in landfills. Given this, in your opinion, would it be fair to ban disposable diapers?" 84% responded no. (Data from EESEE.) Which type of bias does this poll suffer from?

Answer 26

Wording effect as one favors the other

Question 27

A researcher wonders if listening to classical music will improve subjects' abilities to memorize a list of words. She asks 5 students to listen to music while memorizing the words. Another group of students does not listen to music while memorizing the words. All the subjects are then tested to see how many of the words they remember, and the researcher observes the results. This is a(n) __________

Answer 27

experiment

Question 28

When making decision to build a campus dormitory, a university that has many commuter students wants to know the percentage of students who prefer to live in a campus dormitory. The population of interest is the collection of __________

Answer 28

all students at this university

Question 29

In a __________ study, researchers enroll subjects from a common demographic background and observe them at regular intervals over an extended period of time.

Answer 29

Cohort

Question 30

In a survey about a new immigration law in Georgia, "46% of the 132 Georgia farmers, agricultural processors, and farm service businesses who responded said they were experiencing some degree of labor shortage" (Al Hackle, "Groups seek reform, not repeal," Statesboro Herald, June 23, 2011). The 132 who responded is the ______________.

Answer 30

sample

Question 31

A researcher wonders if children who engage in active play for at least 10 minutes a day have a lower obesity rate than children who do not. Staff from her laboratory shadow 100 children for 1 week and record the number of minutes of active play each child participated in each day. They also record the child's weight and BMI to assess obesity.

Answer 31

an observational study

Question 32

A __________ design tells us how to select the sample.

Answer 32

sampling

Question 33

One line from the Table of Random Digits is shown below. Use the random digits to generate 5 random numbers between 01 and 49. The third random number is _____. 14459 26056 31424 80371 65103 62253 22490 61181

Answer 33

31

Question 34

"Ann Landers" is famous for giving advice. Once, in response to a letter from an engaged couple, she asked her readers to write and respond to the question "If you could do it over again, would you have children?" She received over 10,000 responses, 70% of whom said they would not have had children if they could do it over again. These results __________.

Answer 34

don't indicate much due to voluntary response

Question 35

A study that contacts participants at regular time intervals to collect relevant information about events that occur __________ of the study is called a prospective study.

Answer 35

after the start

Question 36

A study of a violent crime rates in a city found that the rates of violent crimes were highest on the days when ice cream sales were also high. A researcher would like to conclude that eating ice cream may be a cause of violent behavior. The effect of ice cream sales on violent crime may be confounded with the effect of temperature. Thus temperature is a potential __________ variable.

Answer 36

lurking

Question 37

The National Survey of Student Engagement (NSSE) regularly surveys freshmen and seniors at colleges and universities about their experiences both in and out of the classroom. Random samples from participating schools are selected, then students are asked and encouraged to complete the survey. At one university there are 3523 freshmen; a sample of 1000 of these is desired. We will use the random digits below to select the first four student labels to be included in the sample. Random Digits: 14459 26056 31424 80371 65103 62253 22490 61181 34041 If we label the 3523 students from 0001 to 3523, the second student selected in the sample is

Answer 37

0371

Question 38

A Gallup poll sponsored by the disposable diaper industry asked, "It is estimated that disposable diapers account for less than 2% of the trash in today's landfills. In contrast, beverage containers, third-class mail and yard waste are estimated to account for about 21% of the trash in landfills. Given this, in your opinion, would it be fair to ban disposable diapers?" 84% responded no. (Data from EESEE.) The _____ of the question introduced bias in this poll.

Answer 38

wording

Question 39

A researcher wonders if listening to music will help students memorize a list of words. She gives the students the list to take home and memorize. The next day the researcher asks each student whether or not they listened to music while memorizing the words. All the subjects are then tested to see how many of the words they remember. What type of study is this?

Answer 39

An observational study

Question 40

what is a case control study

Answer 40

In a case-control study, case-subjects are selected as a random sample of individuals with a condition of interest, and control-subjects are selected as a random sample of individuals without the condition. The two groups are then compared to help identify factors which may be associated with the condition.

Question 41

Define discrete variable

Answer 41

a variable with a finite number of possible values. (whole numbers) "listing of counting"

Question 42

define continuous variable

Answer 42

a variable with an infinite number of possible values (numbers that can be rounded off) Examples are measurements: "length, time, and weight"

Question 43

define single-value grouping

Answer 43

a method of grouping in which each class represents a single possible value

Question 44

define cutpoint grouping

Answer 44

used with continuous data and each group contains a range of values. difference between each group is the width.

Question 45

what are the rules for the cutpoint grouping?

Answer 45

1. number of classes should be between 5 and 20 2. all values must be include and each value belongs ONLY to one class 3. all classes share the same width 4. If possible, class width should be a whole number (max value-min value) / (# of classes)

Question 46

Define Stratified Random sampling

Answer 46

the division of a population into smaller groups from which the random samples are selected.

Question 47

Define simple random sampling

Answer 47

𝑛 individuals from the population chosen in such a way that every set of 𝑛 individuals has an equal chance to be the sample actually selected.

Question 48

Define Random Cluster Sampling

Answer 48

divides the population into groups. Geographically chooses the chosen cluster and uses those samples that were randomly chosen. For example, only uses mice from box 6

Question 49

Define Voluntary Sampling (biased) also known as volunteer or self-selected sample

Answer 49

Let individuals choose whether to participate in the study (write-ins, call-ins, or online quick votes)

Question 50

Define the Systematic sampling method

Answer 50

creating a sorted list of the population, randomly choosing the first participant to include in the sample, and selecting every 𝑛th participant after the first one until enough participants are selected for the sample.

Question 51

Define The Convenience Sampling method

Answer 51

selecting the most easily accessible items from the population for the sample

Question 52

Define unblinded Study

Answer 52

both the experimenter and the subject know which treatment the subject is receiving

Question 53

Define single-blind study

Answer 53

Neither the experimenter nor the subject knows the which treatment is being administered, but not both

Question 54

define double-blind study

Answer 54

both the researcher and the subject are unaware of which treatment was administered

Question 55

Define Response bias

Answer 55

the behavior of the respondent

Question 56

define nonresponse bias

Answer 56

when a selected individual cannot be contacted or refuses to participate

Question 57

define undercoverage sampling or coverage bias

Answer 57

When some groups in the target population are left out of the process of selecting the sample

Question 58

What is the definition that links population and sample?

Answer 58

A population is the complete group under study. A sample is the sub-collection of members of the population from which data are collected