AP Statistics 2017

(Marvins-Underground-K-12) #1
environment in  which   the experiment  was conducted.  The randomization   controlled  for
unknown influences that might be present in the various tank locations.
You will need to recognize paired data, as distinct from two independent sets of data, later on
when we study inference. Even though two sets of data are generated in a matched-pairs study, it is
the differences between the matched values that form the one-sample data used for statistical
analysis.

Exam    Tip: You    need    to  be  clear   on  the distinction between the purposes    for blocking    and randomizing.
If you are asked to describe an experiment involving blocking, be sure to remember to randomize
treatments within blocks.

Rapid Review




  1.      You are doing   a   research    project on  attitudes   toward  fast    food    and decide  to  use as  your    sample  the

    first 25 people to enter the door at the local FatBurgers restaurant. Which of the following is (are)
    true of this sample?
    a. It is a systematic sample.
    b. It is a convenience sample.
    c. It is a random sample.
    d. It is a simple random sample.
    e. It is a self-selected sample.
    Answer : Only (b) is correct. (a), (c), and (d) are all probability samples, which rely on some random
    process to select the sample, and there is nothing random about the selection process in this situation.
    (e) is incorrect because, although the sample members voluntarily entered Fat Burgers, they haven’t
    volunteered to respond to a survey.



  2. How does an experiment differ from an observational study ?


Answer  :   In  an  experiment, the researcher  imposes some    treatment   on  the subjects    (or experimental
units) in order to observe a response. In an observational study, the researcher simply observes,
compares, and measures, but does not impose a treatment.



  1.      What    are the three   key components  of  an  experiment? Explain each.



Answer  :   The three   components  are randomization,  control,    and replication.    You randomize   to  be  sure
that the response does not systematically favor one outcome over another. The idea is to equalize
groups as much as possible so that differences in response are attributable to the treatment variable
alone. Control is designed to hold confounding variables constant (such as the placebo effect).
Replication ensures that the experiment is conducted on sufficient numbers of subjects to minimize the
effects of chance variation.



  1.      Your    local   pro football    team    has just    suffered    a   humiliating defeat  at  the hands   of  its archrival.  A

    local radio sports talk show conducts a call-in poll on whether or not the coach should be fired. What



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