Lab 11 Worksheet
Name:
UID:
Section Meeting Time:
Each question lays out a research question. State the null hypothesis H0 and the
alternative hypothesis H1 in each case. Include exactly what each hypothesis says about
the population parameter (μ). See the lab for examples.
1.
In short-term memory tasks such as the digit span task, people typically can
recall a sequence of about μ = 7 (σ =2) digits accurately when the numbers are
presented at a rate of 1 digit per second. A researcher believes that short-term
memory is actually much worse than this. The researcher believes that people are
enhancing their performance not only because the numbers or retained in shortterm memory but also because they rehearse the order of the numbers subvocally
as they are being presented (i.e., people say the numbers over and over in their
heads as fast as they can as the numbers are being presented). The researcher
believes that digit span performance will be much worse if participants are
prevented from engaging in subvocal rehearsal. Participants (N = 44) are given
the normal digit span task but are instructed to repeatedly say the word “the”
aloud as fast as they can while they the numbers are presented to them. This
instruction is designed to prevent subvocal rehearsal without interfering too
much with people’s ability to concentrate because saying “the” repeatedly is
fairly easy.
a. H0:
b. H1:
2.
N = 30 people take a standardized math test while listening to the rock 'n roll
band Pink Freud. Their average score is 94. Did listening to Pink Freud have an
effect on math performance? Assume that in the population, μ = 70 and σ =65 on
the math test.
a. H0:
b. H1:
3.
If N = 10 people receive Schneider Therapy for Depression and their mean score
on the Schneider Depression Inventory is 59, is the therapy effective in reducing
depression? Assume that in the population, μ = 50 and σ =32 on the Schneider
Depression Inventory (higher scores indicate higher depression levels).
a. H0:
b. H1:
4.
N = 15 people show up for a job interview. They take personality test that
includes a subscale called Psychopathic Deviance. Their average score on the
subscale is 34. The owner of the firm believes that these scores are unusually
low and not at all representative of the population. Assume that in the
population, μ = 68 and σ =58 on the Psychopathic Deviance subscale.
a. H0:
b. H1:
5.
A poor performing school is worried about likely consequences mandated by the
No Child Left Behind Act and thus try a new reading program. The new program
has never been tried before and it is not clear if it is helpful or harmful. After a
semester of using the program, N = 25 third graders are randomly selected for
testing and the sample’s average score is 217 on the reading test. The average
score in the school previously for third graders at mid-year had been μ = 200 (σ
=50). The administrators wish to know how the reading program is affecting
reading performance.
a. H0:
b. H1:
6.
The examinations in a large chemistry class are scaled after grading so that the
mean score is μ = 50. The professor thinks that one teaching assistant is a poor
teacher and suspects that this TA’s students will have a lower mean than the
class as a whole. The TA's students this semester can be considered a sample
from the population of all students in the course, so the professor compares their
mean score with overall class average.
a. H0:
b. H1:
Review Questions
7.
If a population has a standard deviation of σ=8, what is the standard error if the
sample size is N=10? Round to 2 decimal places.
8.
DELETE all the wrong answers below: The standard error of the sample mean
is influenced by
the variability of the population ()
the mean of the population
the sample size
DELETE all the wrong answers below: Which r value represents the strongest
correlation?
2.5
0.80
-0.99
0.60
0
9.