- E—An in-depth examination, usually over an
extended period of time, characterizes the case
study method. - D—Correlational research examines the relation-
ship between two variables. Questionnaires or
interviews that ask questions about political party
membership and attitude toward the death
penalty distributed to a large representative
sample of the population could gather appropri-
ate data for the study. Questionnaires and inter-
views are kinds of surveys. - B—People who have close friendships tend to be
happy. Lonely people tend to be unhappy. The
presence of close friendships predicts happiness.
An adult’s weight and running speed (A), sense of
humor and years of education (C), and visual
acuity and salary (E) are unrelated pairs of factors.
Impoverished people are less likely to be healthy
than people who have more money, so (D) indi-
cates an inverse relationship or negative correlation. - D—He is gathering information in the field
about typical behavior of people without manip-
ulating any variables, which characterizes natural-
istic observation. - A—Only controlled experiments can establish
cause and effect relationships. - A—The range is $90,000 to $15,000, or
$75,000. To find the range, deduct the lowest
score from the highest score. - D—The mean is determined by adding all of the
scores and then dividing by the number of scores.
$300,000 10 =$30,000. The median is the
middle score in the ordered distribution. Since
there is an even number of scores in the distribu-
tion, the median is halfway between the 5th and
6th scores, or $20,000. The most frequent score
or mode is $15,000, so the mean is higher than
both the median and the mode. - B—A frequency polygon is a line graph. A posi-
tively skewed distribution has scores clustered
toward the low end of the range and a small
number of unusually high scores. If you draw the
graph with the value of scores on the Xaxis and
the frequency of scores on the Yaxis, you can see
that the tail is on the right or more positive side
of the graph.
62 STEP 4. Review the Knowledge You Need to Score High
Rapid Review
Theories—organized sets of concepts that explain phenomena.Hypothesis—prediction of how two or more factors are likely to be related.Replication—repetition of the methods used in a previous experiment to see whether
the same methods will yield the same results.Independent variable (IV)—the factor the researcher manipulates in a controlled
experiment (the cause).Dependent variable (DV)—the behavior or mental process that is measured in an
experiment or quasi-experiment (the effect).Population—all of the individuals in the group to which the study applies.Sample—the subgroup of the population that participates in the study.Random selection—choosing of members of a population so that every individual has
an equal chance of being chosen to participate in a study.Experimental group—the subgroup of the sample that receives the treatment or inde-
pendent variable.Control group—the comparison group; the subgroup of the sample that is similar to
the experimental group in every way except for the presence of the independent variable.http://www.ebook3000.com