Problem 12 in Chapter 9 described a study that examined
the spotlight effect, which refers to people overestimating
the extent to which others notice their
appearance or behavior. In the study, n = 9 participants
were asked to put on a Barry Manilow T-shirt
and walk into a room where other students were
working. Later, the participants were asked to estimate
how many students in the room noticed the shirt. The
average estimate for the nine participants was M = 6.4
with SS = 162.
a. Make a point estimate of the number of people that
participants think noticed the shirt.
b. Compute the 90% confidence interval for the mean
number of people.
c. After interviewing the students in the room, the
researchers found that an average of μ = 3.1 students
actually noticed the shirt. Based on this value
and your answers from a and b, how much do people
overestimate t