For each question , state the statistical procedure you would use and why it is
ID: 3227983 • Letter: F
Question
For each question , state the statistical procedure you would use and why it is the
most†appropriate. A good answer would take 1-3 sentences. No calculations are required!
7. A professor is curious as to how her class of n=122 is currently performing compared to
past sections of the course she has taught at the university. She compares her classes
current mean grade ( M =81, s =4) to past averages at this point in the semester =77.
Which hypothesis test needs to be conducted in order for the professor to determine if her
current class is performing better than past classes using a two-tailed test with =.05?
8. You want to know if apologies have a significant effect on individuals who are
interrupted while playing a game. You take a sample of 100 students and have them play a
computer game that intentionally crashes as they progress. Half of the participants receive
an apology and the other half do not. Afterward, all participants rate their game playing
experience and state whether they received an apology from the game or not. How would
you decide if there is a significant effect?
9. A psychologist is interested in testing whether political party affiliation relates to whether
or not people vote in local elections. She decides to do a study in which she randomly
samples 300 individuals and for each person she determines political party affiliation
(Democrat, Republican, Independent) and she also asks whether or not the person voted in
their most recent local election. What is the most appropriate statistical test to answer the
researcher’s question?
10. A researcher wants to test whether reward size affects the number of trials it takes for a
child to learn a complex task. He decides to use 4 types of reward (very high value, high
value, moderate value, low value). The researcher gets a random sample of 40 4 year old
children and she randomly assigns each child to one of the four reward conditions. She then
runs through the training task with each child as many times as she needs to for the child to
be able to do it successfully on his/her own. The outcome variable is thus the number of
times it takes for the child to succeed. What is the most appropriate statistical test to answer
the researcher’s question?
Explanation / Answer
Q7.
Given that,
population mean(u)=77
sample mean, x =81
standard deviation, s =4
number (n)=122
null, Ho: =77
alternate, H1: !=77
level of significance, = 0.05
from standard normal table, two tailed t /2 =1.98
since our test is two-tailed
reject Ho, if to < -1.98 OR if to > 1.98
we use test statistic (t) = x-u/(s.d/sqrt(n))
to =81-77/(4/sqrt(122))
to =11.045
| to | =11.045
critical value
the value of |t | with n-1 = 121 d.f is 1.98
we got |to| =11.045 & | t | =1.98
make decision
hence value of | to | > | t | and here we reject Ho
p-value :two tailed ( double the one tail ) - Ha : ( p != 11.0454 ) = 0
hence value of p0.05 > 0,here we reject Ho
ANSWERS
---------------
null, Ho: =77
alternate, H1: !=77
test statistic: 11.045
critical value: -1.98 , 1.98
decision: reject Ho
p-value: 0
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