STATS CH.1 HW
Identify the level of measurement of the data, and explain what is wrong with the given calculation. In a survey, the favorite sports of respondents are identified as 10 for basketball, 20 for baseball, 30 for football, and 40 for anything else. The average (mean) is calculated for 690 respondents and the result is
The data are at the nominal level of measurement. because Such data are not counts or measures of anything, so it makes no sense to compute their average
State whether the data described below are discrete or continuous, and explain why. The exact heights of students in a class
The data are continuous because the data can take on any value in an interval.
Determine whether the data described below are qualitative or quantitative and explain why. The heights of subjects in a clinical trial of a new drug
The data are quantitative because they consist of counts or measurements.
Determine whether the given description corresponds to an observational study or an experiment. In a study of 354 children with a particular disease, the subjects were given certain drugs to determine if the drugs have an effect on the disease.
The given description corresponds to an experiment.
Identify which of these designs is most appropriate for the given experiment: completely randomized design, randomized block design, or matched pairs design. Currently, there is no approved vaccine for the prevention of infection by a certain virus. A clinical trial of a possible vaccine is being planned to include subjects treated with the vaccine while other subjects are given a placebo.
The most appropriate is completely randomized design.
Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most appropriate for the data below. Types of movies (drama, comedy, adventure, documentary, etc.)
The nominal level of measurement is most appropriate because the data cannot be ordered.
Determine if the following statement represents a meaningful ratio, so the ratio level of measurement applies. A movie with a 4-star rating is twice as good as one with a 2-star rating.
The ratio level of measurement does not apply.
Determine whether the study is an experiment or an observational study, and then identify a major problem with the study. A study involved 22,071 male physicians. Based on random selections, 11,037 of them were treated with aspirin and the other 11,034 were given placebos. The study was stopped early because it became clear that aspirin reduced the risk of myocardial infarctions by a substantial amount. What is a major problem with the study?
The results apply only to male physicians.
Determine whether the source given below has the potential to create a bias in a statistical study. Washington University obtained word counts from the most popular novels of the past five years.
There does not appear to be a potential to create a bias. The organization would not gain from putting a spin on the results.
Determine whether the study is an experiment or an observational study, and then identify a major problem with the study. A study involved 22,071 male physicians. Based on random selections, 11,037 of them were treated with aspirin and the other 11,034 were given placebos. The study was stopped early because it became clear that aspirin reduced the risk of myocardial infarctions by a substantial amount. This is an__________because the researchers_____________the individuals.
This is an experiment because the researchers apply a treatment to the individuals.
Determine whether the study is an experiment or an observational study, and then identify a major problem with the study. A sociologist has created a brief survey to be given to 2000 adults randomly selected from the U.S. population. Here are her first two questions: (1) Have you ever been the victim of a felony crime? (2) Have you ever been convicted of a felony? This is an___________because the researcher______________the individuals.
This is an observational study because the researcher does not attempt to modify the individuals.
Determine whether the results below appear to have statistical significance, and also determine whether the results have practical significance. In a study of a weight loss program, 5 subjects lost an average of 46 lbs. It is found that there is about a 38% chance of getting such results with a diet that has no effect.Does the weight loss program have practical significance?
Yes, the program is practically significant because the amount of lost weight is large enough to be considered practically significant.
Determine whether the results below appear to have statistical significance, and also determine whether the results have practical significance. In a study of a weight loss program, 5 subjects lost an average of 46 lbs. It is found that there is about a 38% chance of getting such results with a diet that has no effect.Does the weight loss program have statistical significance?
No, the program is not statistically significant because the results are likely to occur by chance.
Which sampling method subdivides the population into categories sharing similar characteristics and then selects a sample from each subdivision?
stratified
A newspaper posted this question on its website: "How often do you seek medical information online?" Of 1072 Internet users who chose to respond, 38% of them responded with "frequently." What term is used to describe this type of survey in which the people surveyed consist of those who decided to respond? What is wrong with this type of sampling method?What is wrong with this type of sampling method? Select all that apply.
-Many people may choose not to respond to the survey. -Responses may not reflect the opinions of the general population.
A newspaper posted this question on its website: "How often do you seek medical information online?" Of 1072 Internet users who chose to respond, 38% of them responded with "frequently." What term is used to describe this type of survey in which the people surveyed consist of those who decided to respond? What is wrong with this type of sampling method? what term is used to describe this survey?
-The respondents are a self-selected sample. -The respondents are a voluntary response sample.
Determine whether the study is an experiment or an observational study, and then identify a major problem with the study. A sociologist has created a brief survey to be given to 2000 adults randomly selected from the U.S. population. Here are her first two questions: (1) Have you ever been the victim of a felony crime? (2) Have you ever been convicted of a felony?What is a major problem with the study?
Individuals convicted of a felony are more likely to not answer the second question honestly.
Determine whether the sampling method described below appears to be sound or is flawed. In a survey of 592 human resource professionals, each was asked about the importance of the age of a job applicant. The survey subjects were randomly selected by pollsters from a reputable market research firm.
It appears to be sound because the data are not biased in any way.
Determine whether the underlined number is a statistic or a parameter. A sample of employees is selected and it is found that 65% own a television.
Statistic because the value is a numerical measurement describing a characteristic of a sample.
Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in the situation described below. A woman is selected by a marketing company to participate in a paid focus group. The company says that the woman was selected because she was randomly chosen from all women in her tax bracket.
Stratified sampling
Identify the type of sampling used: random, systematic, convenience, stratified, or cluster. To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Daimler−Chrysler selects every 18th van that comes off the assembly line starting with the fifth until she obtains a sample of 80 vans.
Systematic
Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in the situation described below. A man experienced a tax audit. The tax department claimed that the man was audited because everyone in six randomly selected districts was being audited.
cluster sampling
Identify the type of observational study. A researcher plans to obtain data by interviewing relatives of victims who perished in a bombing to see how they're coping now.
cross- sectional
Identify the type of observational study (cross-sectional, retrospective, or prospective) described below. A research company uses a device to record the viewing habits of about 5000 households, and the data collected over the next 8 years will be used to determine whether the proportion of households tuned to a particular news program decreases.Which type of observational study is described in the problem statement?
prospective study
