Upload
salie-lim
View
219
Download
0
Embed Size (px)
Citation preview
8/7/2019 Review Test Submission_ Coursework1
http://slidepdf.com/reader/full/review-test-submission-coursework1 1/4
ECON10062 Introductory Statistics 2010-11 2nd Sem es ter Course Content Coursew ork 1 Review Test Submission: Coursework1
Review Test Submission: Coursework1
User Shu Lim
Submitted 04/03/11 20:24
Name Coursework1
Status Completed
Score 4 out of 10 points
Time
Elapsed
34 minutes and 10 seconds out of 2 hours.
Instructions Read the instructions file that was publ ished in the relevant Blackboard Folder.
Follow the ins tructions given in that file BEFORE you start this tes t. You will be
presented with 10 ques tions which are randomly drawn from a larger pool of
questions. Each question has only one correct answer and is worth one point. This
assess ment will contribute 5% of your overall grade.
ECON10062
Introductory
Statistics 2010-11
2nd Semester
Noticeboard
Course Content
Additional Media
Communication
Course Information
Assessment
My Grades
Learning Resources
eLearning Support
Staff DetailsQuestion 1
This ques tion refers to the infstudy and the cjspolb variables of the British Crime
Survey dataset on Blackboard. What is the observed joint probability of picking a
respondent that is not full-time s tudent and not confident (this includes 'not very'
and 'not at all') that the police is effective at catching criminals?
Selected
Answer:
0.47232
Correct
Answer:
0.00855
Answer
Feedback:
wrong. This is P(not confident) = P(not very confident) + P(not
at all confident).
Response
Feedback:
revise the s tructure of jo int frequency and probability tables. Also
remember that you can add the probabili ties of two (or more)mutually exclusive categories .
Question 2
You have the following sample observations for the variable X: 45,78,56,74,63
and 45. Which of the following are correct describtive s tatistics?
Selected Answer: Mean = 60.1667, variance = 198.9667, skewness =
0.1418
Correct Answer: Mean = 60.1667, variance = 198.9667, skewness =
0.1418
Answer
Feedback:
correct
Response Feedback: well done
Question 3
0 out of 1 points
1 out of 1 points
0 out of 1 points
04/03/2011 Review Test Submission: Coursework1
online.manchester.ac.uk/…/review.jsp… 1/4
8/7/2019 Review Test Submission_ Coursework1
http://slidepdf.com/reader/full/review-test-submission-coursework1 2/4
This question refers to variable (fairatt5) in the British Crime Survey dataset on
Blackboard, ignoring all respondents that do not answer the ques tion. Which of
the following statements is correct?
Selected
Answer:
About 40.8% of respondents believe that the British Criminal
Justice System is too soft on those accused of crime.
Correct
Answer:
More than 80% of respondents believe that the British Criminal
Justice System is too soft on those accused of crime.
Answer
Feedback:
Incorrect, 40.8% is the proportion of respondents that s trongly
agree 'that the CJS is soft on accused offenders'. However there is
another 39.9% who tend to agree with this statement. You shouldadd these two categories.
Response
Feedback:
These are ordinal data. Once you established the frequency for the
respons es 1 to 4, and then calculated the corresponding
probabilities you should easily answer this question.
Question 4
You have the following sample observations for the variable X: 45,78,56,74,63
and 45. What are the standardis ed Z value for the 3rd and 4th of these
observations?
Selected Answer: Z(X3) = -0.2954, Z(X4) = 0.9807
Correct Answer: Z(X3) = -0.2954, Z(X4) = 0.9807
Answer Feedback: correct
Response Feedback: well done
Question 5
Which of the following s tatements regarding measures of central tendency is
correct?
Selected
Answer:
When a distribution is symmetric the mean and median
will be very similar.
Correct
Answer:
When a distribution is symmetric the mean and median
will be very similar.
Answer
Feedback:
correct
Response Feedback: good work
Question 6
What is the correct measure of central tendency for the variable fairatt5 of the
British Crime Survey? Ignore all respondents that did not answer.
Selected
Answer:
Either Median = 2 or Mean = 1.8217
Correct
Answer:
Either Median = 2 or Mode = 1
Answer
Feedback:
Incorrect, these are categorical (ordinal) data. The mean cannot be
interpreted. The Median was correctly calculated
Response
Feedback:
revise how to calculate measures of central tendency and ens ure
you know when the mean can be calculated
Question 7
1 out of 1 points
1 out of 1 points
0 out of 1 points
0 out of 1 points
04/03/2011 Review Test Submission: Coursework1
online.manchester.ac.uk/…/review.jsp… 2/4
8/7/2019 Review Test Submission_ Coursework1
http://slidepdf.com/reader/full/review-test-submission-coursework1 3/4
You have the following joint frequency table for the two variables pubeve (PV,
asks for frequency of visits to a pub, 1=no visits, 2=less than once a week,
3=once to twice a week, 4=at least 3 times a week) and nchil (NC, asks for
number of children under 16 in household):
pubeve
nchil 1 2 3 4
none 4374 2037 1491 591 8493
one 603 501 218 88 1410
at least 2 749 593 267 57 1666
5726 3131 1976 736 11569
What is the probability distribution for number of children (NC) conditional on the
respondent going to the pub at least three times a week (PV = 4)?
Selected
Answer:
P(NC=0|PV=4) = 0.0511, P(NC=1|PV=4) = 0.0076,
P(NC=2|PV=4) = 0.0049
Correct
Answer:
P(NC=0|PV=4) = 0.8030, P(NC=1|PV=4) = 0.1196,
P(NC=2|PV=4) = 0.0774
Answer
Feedback:
wrong, you report the joint probabilities, e.g. P(PV=1 AND NC=2).
This cannot be a probability distribution as the probabilities do not
sum to one.
Response
Feedback:
revise how to derive conditional probabilities from a
frequency table.
Question 8
This ques tion refers to the infstudy and the cjspolb variables of the British Crime
Survey dataset on Blackboard. What is the probability of a respondent being fairly
confident in the pol ice (being effective at catching criminals) conditional on the
respondent not being a full-time s tudent?
Selected
Answer:
0.4754
Correct
Answer:
0.4844
Answer Feedback:
wrong, you multiplied P(fairly confident) with P(not student). That isnot the observed conditional probability.
Response
Feedback:
revise the structure of joint frequency and probability tables and
the definition of conditional probabili ties.
Question 9
Which of the following s tatements regarding his torical probabilities is correct?
Selected
Answer:
Historical probabilities can be a guide for the probability of
future events if they have been derived from a large s ample that is
representative for the circumstances considered.
Correct
Answer:
Historical probabilities can be a guide for the probability of
future events if they have been derived from a large s ample that isrepresentative for the circumstances considered.
Answer
Feedback:
correct
Response Feedback: well done
Question 10
0 out of 1 points
1 out of 1 points
0 out of 1 points
04/03/2011 Review Test Submission: Coursework1
online.manchester.ac.uk/…/review.jsp… 3/4
8/7/2019 Review Test Submission_ Coursework1
http://slidepdf.com/reader/full/review-test-submission-coursework1 4/4
Friday, 4 March 2011 20:25:23 o'clock GMT
You have the following joint frequency table for the two variables pubeve (asks for
frequency of visits to a pub, 1=no visits, 2=less than once a week, 3=once to
twice a week, 4=at least 3 times a week) and nchil (asks for number of children
under 16 in hous ehold):
pubeve
nchil 1 2 3 4
none 4374 2037 1491 591 8493
one 603 501 218 88 1410
at least 2 749 593 267 57 1666
5726 3131 1976 736 11569
What is the probability distribution for num ber of pub visits (PV) conditional on
there being at least two children in the household (NC = 2)?
Selected
Answer:
P(PV=1|NC=2) = 0.0647, P(PV=2|NC=2) = 0.0513,
P(PV=3|NC=2) = 0.0231, P(PV=4|NC=2) = 0.0049
Correct
Answer:
P(PV=1|NC=2) = 0.4496, P(PV=2|NC=2) = 0.3559,
P(PV=3|NC=2) = 0.1603, P(PV=4|NC=2) = 0.0342
Answer
Feedback:
wrong, you report the joint probabilities, e.g. P(PV=1 AND NC=2).
This cannot be a probability distribution as the probabilities do not
sum to one.
Response
Feedback:
revise how to derive conditional probabilities from a
frequency table.
OK
04/03/2011 Review Test Submission: Coursework1
online.manchester.ac.uk/…/review.jsp… 4/4