BAI 210 exam 1

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

Which of these are possible dangers of​ nonresponse? Select all that apply.

-Those who feel strongly about the subject are more likely to respond. -Those who do not feel strongly about the subject are less likely to respond.

Data on the​ length, in​ seconds, of a sample of 50 songs by The Beatles are presented in the accompanying data table. Complete parts​ (a) through​ (d) below.

Both the frequency histogram and the dotplot show most of the values being clustered between 100 and 200 seconds. The dotplot allows for showing the relative positions of the data more precisely.

descriptive statistics

consists of organizing and summarizing information​ collected

What is the acronym used for simple random sampling without​ replacement?

SRR

The members of a population have been numbered 1-50. A sample of size 20 is to be taken from the​ population, using cluster sampling. The clusters are of equal size​ 10, where cluster​ #1 consists of the members of the population numbered 1-​10, cluster​ #2 consists of the members of the population numbered 11-​20, and so forth. a. What are the clusters taken from the​ population?

1-​10, 11-​20, 21-​30, 31-​40, 41-50

In a designed​ experiment, there is one factor with four levels. How many treatments are​ there?

4

According to​ Chebyshev's rule, at least ... of the observations in any data set lie within 2.5 standard deviations to either side of the mean.

84%

According to​ Chebyshev's rule, at least enter your response here​% of the observations in any data set lie within four standard deviations to either side of the mean.

93.75%

What is a truncated​ graph?

A graph where part of the one of the axes has been cut off or truncated

Percentage vs relative frequency

A relative frequency is the same as a percentage expressed as a decimal.

One characteristic measured about high schools is the percent free​ lunch, which is the percentage of the student body that is eligible for free and​ reduced-price lunches. The top 100 ​schools, grouped according to their percent free​ lunch, is as shown in the accompanying table. Complete parts​ (a) and​ (b) below.

Choose 55​/100 of the sample from 0-under 10​, choose 16​/100 of the sample from 10-under 20​, choose 6​/100 of the sample from 20-under 30​, choose 6​/100 of the sample from 30-under 40​, and choose 17​/100 of the sample from 40 or over. Multiply each fraction by 25 to get the sample size for each​ group, adjusting the values to integers if needed. Then use a random number generator to select the chosen number of schools from each group.

What are the two major types of​ statistics? Describe them in detail.

Descriptive statistics consists of organizing and summarizing information​collected, while inferential statistics uses methods that generalize results obtained from a sample to the population and measure the reliability of the results.

What are the two major types of​ statistics?

Descriptive and Inferential

b. Choose the correct answer below.

In a designed​ experiment, researchers impose treatments and controls and then observe characteristics and take measurements.

a. Choose the correct answer below.

In an observational​ study, researchers simply observe characteristics and take​ measurements, as in a sample survey.

Complete the following​ statement: A descriptive measure is resistant if...

It is not sensitive to the influence of a few extreme observations.

Give a legitimate motive for truncating the axis of a graph. Choose the correct answer below.

It may allow relevant information to be conveyed more easily.

Presented below is a​ "data scenario." Decide which type of grouping​ (single-value, limit, or​ cutpoint) is probably the best. The times, rounded to the nearest minute, of athletes in a marathon

Limit grouping is probably the best because the data are whole numbers and there are a large number of distinct values.

Do the concepts of class​ limits, marks,​ cutpoints, and midpoints make sense for qualitative​ data? Explain your answer.

No. Class​ limits, marks,​ cutpoints, and midpoints make sense only for numerical​ data, because doing arithmetic for qualitative data is not meaningful.

Ordinal data is data about order or rank given on a scale such as​ 1, 2,​ 3, ... or​ A, B,​ C, ... Does the following variable yield ordinal​ data? Gender

No​, because the data are not ordered in some way

Select the correct choice that completes​ the sentence below.

Observational studies can reveal only​ association, whereas designed experiments can help establish causation

If you have a legitimate motive for truncating the axis of a​ graph, how can you correctly obtain that objective without creating the possibility of​ misinterpretation?

Start the axis at 0 and include a special​ symbol, such as​ slashes, to indicate that part of the axis is missing.

Select the correct choices that complete​ the sentence below.

Systematic random sampling is easier to execute than simple random sampling and usually provides comparable results. The exception is the presence of some kind of cyclical pattern in the listing of the members of the population.

b. Which measure of variation is preferred when the median is used as a measure of​ center?

The interquartile range is preferred when the median is used as a measure of center.

a. Which measure of variation is preferred when the mean is used as a measure of​ center?

The standard deviation is preferred when the mean is used as a measure of center.

A board of governors publishes information on family net worth. In​ 2010, the mean net worth of families in a particular country was ​$456.1 thousand and the median net worth was ​$78.3 thousand. Which measure of center do you think is more​ appropriate? Explain your answer

The median because it is not strongly affected by the relatively few families with extremely high net worth.

b. Is the percentage provided a descriptive statistic or an inferential​ statistic? Explain your answer.

The percentage is a descriptive​ statistic, since it summarizes information about how much of the sample favors breaking up the megabanks.

A nationwide survey of 1000 adults found that 50​% of respondents favored a plan to break up the 12​ megabanks, which then controlled about 69​% of the banking industry. Complete parts​ (a) and​ (b) below. a. Identify the population and sample for this study. Choose the correct answer below.

The population is all adults in the country. The sample is the 1000 adults surveyed.

Explain in detail the purpose of a measure of center.

The purpose of a measure of center is to indicate where the center or most typical value of a data set lies.

b. What does it​ measure?

The range of the middle​ 50% of the observations

Why is obtaining a representative sample​ important?

The sample must be representative in order to use inferential statistics to draw conclusions about the entire population.

What is a consequence of such low response​ rates?

The samples are not likely to be representative of their respective populations.

State whether the investigation in question is an observational study or a designed experiment. Justify your answer. In a paper in a medical​ journal, researchers reported the results of a study of methods for treating patients who had advanced heart failure due to ischemic or nonischemic cardiomyopathies. A total of 1370 patients were randomly assigned in a 1​:1​:2 ratio to receive optimal pharmacologic therapy alone or in combination with either a pacemaker or a​ pacemaker-defibrillator combination. The patients were then observed until they died or were hospitalized for any cause.

The study is a designed experiment because the researchers controlled the treatment of the subjects.

State whether the investigation in question is an observational study or a designed experiment. Justify your answer. In the article​ "One's Sex,​ Sleep, and Posttraumatic Stress​ Disorder", I. Kobayashi et al. study the relationship between​ one's sex, sleep​ patterns, and posttraumatic stress disorder​ (PTSD) after trauma exposure. The authors report that women have a higher lifetime prevalence of PTSD as well as a greater risk of developing PTSD following trauma exposure. Relationships between sleep and physical health have been documented in a number of​ studies, and the authors explore the possibility that disruptive sleep habits are common among people with PTSD and also a possible risk factor for the development of PTSD. A questionnaire of men and women with and without PTSD produced data on their sleep habits. Question content area bottom Part 1 Is the investigation an observational study or a designed​ experiment?

The study is observational because the researchers did not impose any conditions on the subjects before collecting the data.

Classify the study as either descriptive or inferential. Explain your answer. The table below shows data on average professional​ athletes' salaries for the years 2005 and 2011.

The study is​ descriptive, because the statistics are a summary of the average salaries of professional athletes in three sports.

Classify the study as either descriptive or inferential. Explain your answer. A company provides an online database that provides real estate information for homes that are for rent or sale in a certain country. It also presents statistics on recently sold homes. The following table gives various information on all homes sold in several different cities in the country for one month.

The study is​ descriptive, because the table is a summary of the data that was collected.

Classify the study as either descriptive or inferential. Explain your answer. Data from a sample of citizens of a certain country yielded the following estimates of average TV viewing time per month for all citizens 2 years old and older. The times are in hours and​ minutes; Q1 stands for first quarter.

The study is​ inferential, because the statistics are used to make an inference about the population.

Researchers in obesity wanted to compare the effectiveness of dieting with exercise against dieting without exercise.​ Seventy-three patients were randomly divided into two groups. Group​ 1, composed of 38 ​patients, was put on a program of dieting with exercise. Group​ 2, composed of 35 ​patients, dieted only. The results for the weight​ loss, in​ pounds, after 5 months are summarized in the following boxplots. The top boxplot is for Group 1 and the bottom boxplot is for Group 2. Use the boxplots to compare the weight losses for the two​ groups, paying special attention to center and variation.

The weight losses for the two groups​ are, on​ average, roughly the same.​ However, there is less variation in the weight losses of Group 1 than of Group 2.

Name and describe the three most important measures of center.

The​ mean, median, and mode are the most important measures of center. The mean of a data set is its arithmetic average. The median of a data set is the middle value in its ordered list. The mode of a data set is its most frequently occurring value.

c. Which​ stem-and-leaf diagram is more​ useful? Why?

The​ stem-and-leaf diagram with one line per stem is more​ useful, since the shape of the distribution is apparent in both diagrams but the diagram with two lines per stem has a large number of empty stems.

Slightly different methods are used for determining the​ "middle" of a class with limit grouping and cutpoint grouping. Identify the methods and the corresponding terminologies.

With limit​ grouping, the​ "middle" of a class is the average of the two class limits of the​ class; it is called the class mark. With cutpoint​ grouping, the​ "middle" of a class is the average of the two cutpoints of the​ class; it is called the class midpoint.

Which type of variable yields nonnumerical​ data?

qualitative

designed experiment

researchers impose treatments and controls and then observe characteristics and take measurements

observational study

researchers simply observe characteristics and take​ measurements, as in a sample survey. Can reveal only​ association, whereas designed experiments can help establish causation.

A sample distribution is the distribution of

sample data

frequency

the number of times a particular distinct value occurs

relative frequency

the ratio of the frequency of a value to the total number of observations

inferential statistics

uses methods that generalize results obtained from a sample to the population and measure the reliability of the results

Is an extreme observation necessarily an​ outlier? Explain your answer.

​No, it is only a potential outlier. Further data analyses are necessary to determine if it is truly an outlier.

Discuss the relative advantages and disadvantages of​ stem-and-leaf diagrams versus frequency histograms.

​Stem-and-leaf diagrams are easier to make and can contain more information than frequency histograms.​ However, they are not very useful for large data sets.


Kaugnay na mga set ng pag-aaral

Emergence in Global society 1000C: A history of world societies volume 2: Chapter 19: New Worldviews and Ways of life

View Set

Managerial Finance Quiz Ch. 1 & 2

View Set

CH2 Matching Exercises for Organs and Systems #1

View Set

Communication Arts 100 Final Exam *

View Set

5.4 Lines of Credits and Credit Card

View Set

BEC Homework 1 - Chapter 1 and 2

View Set