3.
A researcher has developed a test to measure Acceptance of Psychological
Misconceptions (APM). This scale was given to all students in her Introductory Psychology
course, where they were presented with a lecture on such misconceptions the previous week.
Results indicate that the APM scores for this population (students who attended the lecture) were
normally distributed with a mean of 20.00 and a standard deviation of 4.00. Some students who
were unfortunately absent from the lecture also completed the APM.
The researcher found four test papers left behind in the classroom, and before scoring the
tests, wondered if the students who wrote these tests had likely attended the lecture the week
before (and so should have a mean close to the population mean).
She decided to perform a one-sample Z-test for these four APM test papers, to see if their
mean is too far away from the overall class mean to likely be due to chance variation alone, i.e.,
the scores are so extreme that the four students writing them had probably not attended the
lecture on misconceptions. She decided to use an alpha level of .05.
When asked for hypotheses, provide the symbolic form rather than the worded form.
a) If the researcher was just interested in a possible difference, without regard to whether it was
higher or lower than the class mean, would she want to use a one- or -two tailed test?
b) What is the null hypothesis for this test?
Ho:
c) What is the research hypothesis for this test?
H1:
d) Given that the APM sample mean in question was 17.50 (with n = 4), what is the probability
that the sample was randomly drawn from the population of students who attended the
lecture? (Show the formula and all of your work)
