Each of the 30 major league baseball teams carries a 40-person roster. A sample of 60 players (5% of all 1200 players) is to be randomly selected to undergo drug tests. To do this, each team is instructed to put their 40 names in a hat and randomly draw t
No, because not each group of 60 players has the same chance of being selected.
An advantage to using surveys as opposed to experiments is that
Surveys are generally cheaper to conduct.
A company wishes to survey what the people think about a new product it plans to market. They decide to randomly sample from their customer database as this includes phone numbers and addresses. This procedure is an an example of which type of sampling?
Convenience because they are easy to reach.
Two studies are run to compare the experiences of low-income families receiving food stamps to those receiving cash subsidies. The first study interviews 50 families who have been in each government program for at least 2 years, while the second randomly
The first study is an observational study; the second is an experiment.
A food judge is given an assignment to choose and sample the food at 52 (out of over 20000) NYC restaurants. She has an assistant list all restaurants whose name begins with A, assigns each a number, and uses a random number generator to pick two of these
Her procedure makes use of chance
In a study of parkinson's disease, 100 volunteers had incisions made through their skulls. The patients ere randomly sorted into two groups, one of which had a new drug inserted into the brain. In the other group, the skulls were closed with no treatment
The placebo effect
Fifty migraine patients are randomly selected from hospital records. Half the patients are told to drink ice water and sit in the dark when they next experience a migraine; the remaining patients are told to use neither of these possible remedies. Partici
C. Lack of blinding
Which of the following is most useful in establishing cause-and-effect relationships?
A. a complete census
B. a least squares regression line showing high correlation
C. a simple random sample
D. a well-designed, well-conducted survey incorporating chance
E. A controlled experiment
A sales representative wishes to survey her client base of 47 companies. She has 47 business cards, all of the identical size, from her contacts in the companies, and decides to drop them all in a small box, shake them up, and reach in to pick 5 cards for
Simple random sampling
A newspaper advice columnist asks her readers if they would have married their current spouse if they had it to do over again. Of the 25000 or so responses, 80% said no. What does this show?
The survey is meaningless because of voluntary response bias.
A researcher planning a survey of heads of households in New York has census lists for each of the 62 counties in the state. The procedure will be to obtain a SRS of the heads of households from each of the counties rather than grouping all the census lis
It recognizes that opinions of heads of households in rural NY communities may differ from those in urban communities.
Which of the following is the most important in minimizing the placebo effect?
A. replication and randomization
B. replication and blinding
C. randomization and blinding
D. randomization and a control
E. Blinding and a control
E. Blinding and a Control
In general, for a sample to yield usable results:
A. a sample size of n=30 is usually sufficient
B. Researchers must be careful in the way they word questions
C. Researchers must carefully choose people who are representative of the population
D. a census
B. researchers must be careful in the way they word questions
A bank wishes to survey its customers. The decision is made to randomly pick ten customers who just have checking accounts, ten customers who just have savings accounts, and ten customers who have both checking and savings accounts. This procedure is an e
Stratified
Which of the following is a true statement?
A. If bias is present in a sampling procedure, it can be overcome by dramatically increasing the sampling size
B. There is no such thing as a "bad sample"
C. Sampling techniques that use probability techniques e
E. In choosing a sample size, actual sample size is more important then the fraction of the population that is surveyed
To find out a town's average family size, a researcher interviews a random sample of parents arriving at a pediatrician's office. The average family size in the final 100-family sample is 3.48. Is the estimate probably too low or too high?
Too high because it is at a pediatrician's office so it counts out all/almost all of childless families.
Which of the following is a true statement about blocking?
A. Blocking is to experiment design as stratification is to sampling design.
B. By controlling certain variables, blocking can make conclusions more specific.
C. The paired (matched pairs) compari
E. All of the above statements are true about blocking.
How should randomization be used for a randomized block design?
Within each block, randomly pick half the patients to receive the treatment.
What is bias in conducting surveys?
A tendency to favor the selection of certain members of a population.
A human resources department plans to survey 100 of the 3000 employees is available, a random number between 1 and 30 is picked, and the sample consists of the person that far down the list together with every 30th person after that. This procedure is an
Systematic
I. Would you vote for independence for Puerto Rico?
II. Would you support an independent Puerto Rico separate from the US?
Is one of these bias and if so, why?
I is more bias because "independence" has positive connotation and "separate" has negative connotation
To conduct a survey on holiday shopping patterns, a researcher opens a telephone book to a random page, closes his eyes, puts his finger down on the page, and then reads off the next 100 names. Which of the following is not a true statement?
A. the survey
B. the procedure results in a systematic sample
Before taking an exam, students either went to bed at their normal times or were sleep deprived for 4 to 8 hours. Half of each group were given a caffeine pill before taking the exam. Determine the number of factors, levels for each, and number of treatme
Two factors, one with two and one with three levels, six treatments
A TV network conducts a weekly survey to determine the proportion of viewers who watch various programs. For the coming year, they decide to double the sample size. The main benefit of this is to:
A. reduce undercoverage bias
B. reduce nonresponse bias
C.
E. decrease the standard deviation of the sampling distribution
A botanist is running an experiment on two fertilizers that require different amounts of watering. She has 40 test plots, half of which are in sunny locations, and half are in the shade. She randomly selects 10 sunny plots and 10 shady plots for which to
A. the variable, fertilizer and water, are confounded.
Voluntary response samples often (underrepresent/overrepresent) people with strong opinions
overrepresent
A consumer product agency tests kilowatts per hour for a sample of refrigerators, each one of three different sizes. Which of the following is true?
A. there are three explanatory variables and one response variable
B. there is one explanatory variable wi
D. there are three levels of a single explanatory variable
A critical difference between experiments and observational studies is an experiment often suggests a casual relationship, whereas an observational study only suggests an association.
true or false
true
What is a lurking variable?
a lurking variable is a variable that drives two other variables, creating the mistaken impression that the other two variables are related by cause and effect
To survey the opinions of the people attending a particular broadway play, a surveyor plans to select every 25th theater-goer as he or she exits at the conclusion. Will this method result in a SRS?
No, because not every sample of the intended size has an equal chance of being selected
the purposes behind random sampling and random assignment are different
true/false
true
should this be an experiment or an observational study:
studies showing that animals fed low-calorie diets tend to live longer than animals on normal diets
experiment
you wish to survey people who have brought in their cars for service during the past month. You decide to pick a random sample of gas stations in the city and then survey all customers from those stations who had work done during the past month. This proc
Cluster
Suppose you wish to compare the average height of math/science teachers to the average height of english/social studies teachers in your high school. Which is the most appropriate technique for gather the needed data?
A. census
B. sample survey
C. experim
A. census
Sampling error can be eliminated only if a survey is both extremely well designed and extremely well conducted
true/false
false, sometimes it can be unavoidable
Does bias impact a survey
yes, selection bias/nonresponse bias/response bias all impact a survey
A complete census is the only way to absolutely establish a cause-and-effect relationship
true/false
false
Why do we try to guard against confounding when designing experiments?
Confounding can lead to uncertainty as to which variable is causing an effect
Sampling error is
A. the mean of a sample statistic
B. the standard deviation of a sample statistic
C. the standard error of a sample statistic
D. the result of bias
E. the difference between a population parameter and an estimate of that parameter
E. the difference between a population parameter and an estimate of that parameter