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Hodge Podge
Sampling Method
BIASES
Experimental Design
More about dat Experimental
100
What are the two most effective ways of simulating randomness that we have available to us in AP Stats?
A random number table and randInt on the Nspire.
100
"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, 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 her sample" is an example of this kind of sampling method.
Simple Random
100
What is bias in conducting surveys? A. An example of sampling error. B. Lack of control group. C. Confounding variables. D. Difficulty in concluding cause and effect. E. A tendency to favor the selection of certain members of a population.
E. A tendency to favor the selection of certain members of a population.
100
A critical difference between experiments and observational studies is A. an experiment often suggests a causal relationship, whereas an observational study only suggests an association. B. observation studies make use of randomization, whereas experiments do not. C. experiments are generally more cost and time effective than observational studies. D. tests of significance can be used on data collected from experiments but not on data from observational studies. E. experiments are free to choose subjects from an entire population, whereas an observational study only considers a random sample.
A. an experiment often suggests a causal relationship, whereas an observational study only suggests an association.
100
Which of the following best explains why we try to guard against confounding when designing experiments? A. Confounding can lead to bias. B. Confounding can conflict with randomization. C. Confounding can lead to uncertainty as to which variable is causing an effect. D. Confounding can make it more difficult to separate subjects into treatment and control groups. E. Confounding can negate the benefits of blinding.
C. Confounding can lead to uncertainty as to which variable is causing an effect.
200
A basketball player makes 2/3 of his free throws. How would you simulate this using a random number table?
01, 02, 03, 04, 05, 06, 07, and 08 correspond to making the free throw and 09, 10, 11, and 12 correspond to missing a free throw.
200
"A company wishes to survey what 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" is an example of this kind of sampling method.
What is convenience sampling?
200
"Many people believe this playground is too small and in need of repair. Do you think the playground should be repaired and expanded even if that means raising the entrance fee to the park?" is an example of this kind of bias.
What is response bias? Bonus points, if you can describe how it creates bias.
200
Before taking an exam, students either went to bed at their normal times or were sleep deprived 4 or 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 treatments.
Two factors, one with two and one with three levels, six treatments.
200
An advantage to using surveys as opposed to experiments is that. A. surveys are generally cheaper to conduct. B. it is generally easier to conclude cause and effect from surveys. C. surveys are generally not subject to bias. D. surveys involve use of randomization. E. surveys can make sure of stratification.
A. surveys are generally cheaper to conduct
300
Suppose your local school district decides to randomly test high school students from ADD. There are three high schools in the district, each with grades 9-12. The school board pools all of the students together and randomly samples 250 students. Is this a simple random sample?
Yes, because they could have chosen any 250 students from throughout the district
300
A human resources department plans to survey 100 of the 3,000 employees in the firm. An alphabetical list of the 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 example of which type of sampling? A. Cluster B. Convenience C. Simple Random D. Stratified E. Systematic
E. Systematic
300
A news paper advice columnist asks her readers if they would have married their current souse if they had it to do over again. Of the 25,000 or so responses, 80% said no. What does this show?
The survey is meaningless because of voluntary response bias.
300
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 matched pairs comparison design is a special case of blocking. D. Blocking is useful procedure when there are certain attributes, not under study, which may affect the outcomes. E. All of the above are true statements about blocking.
E. All of the above are true statements about blocking.
300
In a study of Parkinson's disease, 100 volunteers had incisions made through their skulls. The patients were 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 given. The patients did not know who received the drug. In the weeks to follow all 100 volunteers showed similar improvement in physical condition. What is this an example of?
The placebo effect
400
Which of the principle of experimental design is not required?
Blocking
400
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. This is an example of...
Systematic sample.
400
Which of the following statements is incorrect? A. Voluntary response samples often underrepresent people with strong opinions. B. Convenience samples often lead to undercoverage bias. C. Questionnaires with nonneutral wording are likely to have response bias. D. There is no way to fix the results if a biased sampling method was employed. E. Nonresponse bias should be avoided because those who do not respond might have different views from those who do respond.
A. Voluntary response samples often underrepresent people with strong opinions.
400
A consumer product agency tests kilowatts per hour for a sample of refrigerators, each one of three different sizes. How many levels are there?
There are three levels of a single explanatory variable.
400
100 volunteers who suffer from depression. 50 were randomly selected to receive a new drug thought to treat severe depression, while 50 others were given an existing drug for treating severe depression. A psychiatrists evaluates all of the symptoms after four weeks in order to determine if there has been a substantial improvement in the severity of depression. The factor is...
Which treatment the volunteers received.
500
Among a dozen eggs, three are rotten. A cookie recipe calls for two eggs; they'll be selected randomly from that dozen. Which plan could be used to simulate the number of rotten eggs that might be chosen? 1. Let 0, 1, and 2 represent the rotten eggs, and 3,4,...,11 the good eggs. Generate two random numbers 0-11, ignoring repeats. 2. Randomly generate a 0,1, or 2 to represent the number of rotten eggs you get. 3. Since 25% of the eggs are rotten, let 0 = rotten and 1, 2, 3 = good. Generate two random numbers 0-3, and see how many 0's you get. A. 1 only B. 2 only C. 3 only D. 1 or 3 only E. 1, 2, and 3
A. 1 only
500
A candy manufacturer wants to test consistency of the sugar content of chocolate-covered cherries produced in one factory. The company decides to randomly select three boxes of chocolate-covered cherries from each day's production run at the factory and analyze every cherry in each of these boxes as to sugar content. What type of sampling is this? A. Cluster B. Convenience C. Simple random D. Stratified E. Systematic
A. Cluster
500
A chemistry professor who teaches a large lecture class surveys his students who attend his class about how he can make the class more interesting, hoping he can get more students to attend. This survey method suffers from...
Voluntary response bias
500
50 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. Participants then report back as to relief, if any. Faults of this experimental design include all of the following except: A. Lack of randomization B. Confounding variables C. Lack of blinding D. Unclear factor levels E. Measurement of response variable
C. Lack of blinding
500
Which of the following statements is incorrect? A. Based on careful use of control groups and random assignment, experiments can often indicate cause-and-effect relationships. B. Although observational studies may suggest relationships, it would be very difficult to conclude cause and effect because of the lack of control over confounding variables. C. A complete census is the only way to absolutely establish a cause-and-effect relationship. D. In order to generalize from samples to the populations they come from, the samples should be selected at random from the populations. E. When treatments are applied to randomly formed groups, cause-and-effect conclusions become possible.
C. A complete census is the only way to absolutely establish a cause-and-effect relationships.