Evaluating reports worksheet
This worksheet will help with review of concepts for NCEA 3.12. Join NZ Stats 3 at
www.statslc.com for many more exercises like these, with immediate feedback.
Sample and Population
1. Sample statistics are known values calculated from the collected data.
True / False
2. The New Zealand Census is a sample.
True/ False
Sampling or Non-sampling error
3. Sampling error occurs when mistakes are made in executing the sampling plan.
True/False
4. Interviewer effects are a potential source of sampling error.
True/False
Sampling methods
In a survey, the researcher is interested in the level of satisfaction travellers to New
Zealand feel with regard to their hotel accommodation. Using a list of the people
entering New Zealand in a year, she uses random number tables to select a random
sample of 500, and sends surveys to their home address.
5.
What is this sampling method called? Cluster sampling/Convenience
sampling/Simple random sampling/Stratified sampling/Systematic sampling
How effective is this sampling method?
A. This is a quick and easy method of sampling.
B. This is an effective way to make sure that various groups were sampled.
C. This is more practical than random sampling and may provide a good
approximation of a random sample.
D. This will give a representative unbiased sample.
6.
Questionnaire Design
7. What is a suitable question in one questionnaire may not be suitable in a
different questionnaire.
True/False
8. You need to think carefully about whether earlier questions will affect the way
people will respond to later questions.
True/False
Evaluating survey questions
We are conducting a survey about gambling among people aged 18 to 30 in New
Zealand. One of the questions in the written questionnaire is as follows:
Do you consider that horse-racing is gambling and therefore jockeys are
not really sportspeople?



Yes
No
No opinion
This worksheet is provided by Dr Nicola Ward Petty and Dr Shane Dye of Statistics Learning Centre.
Copying without acknowledgement of the source violates copyright.
Many more exercises like these, with immediate feedback are available by joining NZ Stats 3 at statslc.com
Page 1
9.
Which of the following BEST describes the question.
A. The question has more than one idea in it.
B. The question could be confusing because it is worded in the negative.
C. The question is "leading" in that it is not stated in a neutral way.
D. The alternative responses are not well-defined.
E. This is a good question for this context.
Experiments and Observational studies
10. When you collect data from processes that are already taking place, this can be
classified as an experiment.
True/False
11. You randomly assign half a class to eat a Weetbix with milk and the other half
to eat a Weetbix without milk and you time them. This is an example of an
experiment.
True/False
12. In an experiment exploring the effect of free stickers on the sales of
choconutties it was thought that the weather may also affect sales. This is
called a lurking variable.
True/False
13. We wish to see how well basketball players know the rules of the game. We
take two teams and give the players a test on the rules, out of ten questions.
Then we compare the median scores of the two teams.
Which of the following best describes the scenario above?
A. This is an observational study.
B. This is a well-designed experiment involving randomisation.
C. This is a poorly designed experiment.
Margin of Error and polls
14. The reported margin of error depends only on the size of the sample. It is most
appropriate for proportions around 0.5.
True/False
15. A well-executed poll will have the same margin of error as a poorly-executed
poll of the same size.
True/False
16. An opinion poll is taken with a sample of size 7500. What will the margin of
error be? Give your answer as a percentage with one decimal place.
17. An opinion poll is taken with a sample of size 80. Of the sample, 60% are men.
What will the margin of error be for proportions reported from the men?
A survey of first year students included 69 women and 99 men. They were asked
how many servings of fruit they generally ate in a day. 30% of the women and 39%
of the men said they ate no fruit or one serving of fruit per day. We are interested
to see if there is evidence of a difference in the population.
18. What is the confidence interval for the difference?
19. Which statement best describes this confidence interval:
A. As this confidence interval contains zero, we do not have evidence that
there is a difference in the population.
B. As the confidence interval contains zero we can reasonably conclude that
more men eat zero or one fruit a day.
C. We do not have enough information to draw any conclusions.
This worksheet is provided by Dr Nicola Ward Petty and Dr Shane Dye of Statistics Learning Centre.
Copying without acknowledgement of the source violates copyright.
Many more exercises like these, with immediate feedback are available by joining NZ Stats 3 at statslc.com
Page 2
Evaluating Reports worksheet
Answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
18.
True – We calculate the sample statistics from the sample and we use them to
make inferences about the population parameters.
False – The NZ Census endeavours to ask the entire population of New
Zealand. It provides population data.
False - Sampling error exists because we are using a sample of observations
rather than the whole population. Sampling error is unavoidable.
False – Interviewers can affect the way people respond, leading to bias or other
non-sampling error. Sampling error occurs regardless of the method of data
collection.
Simple random sampling.
D.
True - You need to think hard about the purpose, the people who are being
surveyed, and the manner in which the survey is being conducted.
True - For example if you have questions about how helpful and friendly a
teacher is, and then get people to rate the teacher overall, this may get a
different response than if you had previous questions about how much the
teacher knew.
A. There are two ideas. Firstly, whether horse-racing is gambling, and secondly,
whether jockeys are sportspeople.
False - For a study to be classified as an experiment it must involve planned
interference in the natural order of events by the researcher. When there is no
intervention, it is an observational study, not an experiment.
True - It is a rather silly experiment because obviously the people without milk
will take longer to eat their Weetbix. However, as there is an intervention providing milk or not, this could be classed as an experiment.
True - Factors that might affect the response variable are known as lurking
variables, confounding variables or hidden factors.
A. The two groups were not assigned randomly, but according to team. There is
no intervention or treatment.
True - The margin of error is largest for proportions of around 0.5, so the
reported margin of error is about right for values near 0.5.
True - A well-executed poll has minimised the non-sampling error, but margin
of error only accounts for sampling error. The reported margin of error depends
on the size of the sample.
1.2%
17. 14.4%
(-7.6%,25.6%)
19. A
To have a 7-day free trial of NZ Statistics 3 at Statistics Learning Centre, go to
http://course.statslc.com/
To find out more about discounted subscription for schools, email n.petty@statslc.com
This worksheet is provided by Dr Nicola Ward Petty and Dr Shane Dye of Statistics Learning Centre.
Copying without acknowledgement of the source violates copyright.
Many more exercises like these, with immediate feedback are available by joining NZ Stats 3 at statslc.com
Page 3