ap stats
does caffeine improve exam performance? suppose half of the students from the 8:30 section of a course are randomly allocated to the treatment group (two cups of coffee) and the other half to the control group (two cups of decaf). in addition, half of the 9:30 students are randomly allocated to the treatment group, the other half to the control group. this is an example of a
Block Design
Which of the following is NOT a major principle of good design for all experiments.
Blocking
a marine biologist wants to estimate the mean size of the barnacle semi Balanus belonids on a stench rocky shoreline. to do so, he randomly selected twenty 10-cm. square plots and measured the size every barnacle in each plot. this is an example of
Cluster Sample
The reason that blocking (as in a randomized block design) is sometimes used in experimentation is to
Compensate for anticipated differences in the response variable for different values of a specified "blocking" variable.
does caffeine improve exam performance? suppose half of the students from the 8:30 section of a course are randomly allocated to the treatment group (two cups of coffee) and the other half to the control group (two cups of decaf). in addition, half of the 9:30 students are randomly allocated to the treatment group, the other half to the control group. this is an example of a
Randomized block design.
Simple random sampling
Reduces bias resulting from the behavior of the interviewer.
A television station is interested in predicting whether voters in its viewing area are in favor of offshore drilling. It asks its viewers to phone in and indicate whether they support/are in favor of or are opposed to this practice. Of the2241 viewers who phoned in, 1574 (70%) were opposed to offshore drilling. The viewers who
a voluntary response sample.
You want to know the opinions of American school teachers about establishing a national test for highs cool graduation. You obtain a list of the members of the national education association (the largest teachers' union) and mail a questionnaire to 2500 teachers chosen at random from this list. In all 1347 teachers return the questionnaire the population is
a. the 1347 teachers who mail back the questionnaire.
for one kindergarten class in his district, a researcher determines which children already can read simple words and which children cannot upon entering kindergarten. the children are followed until 3rd grade, at which point they are tested to determine the grade level at which they are reading. those children who were reading simple words on entering kindergarten are found to be reading at a higher level than those who could not read simple words on entering kindergarten. the researcher
cannot conclude that being able to read before entering kindergarten is beneficial, as there may be confounding variables in this study