A researcher required a sample of 30 university students for a survey. An email
ID: 3335882 • Letter: A
Question
A researcher required a sample of 30 university students for a survey. An email asking
for volunteers was sent out to all students and 24 students then volunteered to complete
the survey. To fill the remaining spots, the researcher selected 6 of his postgraduate
students to completed the survey. This is an example of a bad sample. What are the
two issues that make this a bad sample?
When exploring relationships between variables, there are four features that need to
be considered. A researcher has calculated the correlation coefficient for some data to
be r = —0.9 and using only this information concluded that
The data has a strong, negative, linear relationship.
Determine if the researcher has .a correct conclusion, commenting on each of the four
features.
Tlie histogram of a dataset is shown in Figure 1. The sample mean is 50. Which one
of the following values for the median is consistent with the histogram? Why?
Median = 48 or Median = 52 or Median = 50.
What is the population and parameter for the following study?.
A study conducted in June, 2016 of 6,138 Australians over the age 'of 14 found'
that 54.7% of them had purchased butter in the preceding 12 months.
A researcher required a sample of 30 university students for a survey. An email asking
for volunteers was sent out to all students and 24 students then volunteered to complete
the survey. To fill the remaining spots, the researcher selected 6 of his postgraduate
students to completed the survey. This is an example of a bad sample. What are the
two issues that make this a bad sample?
When exploring relationships between variables, there are four features that need to
be considered. A researcher has calculated the correlation coefficient for some data to
be r = —0.9 and using only this information concluded that
The data has a strong, negative, linear relationship.
Determine if the researcher has .a correct conclusion, commenting on each of the four
features.
Tlie histogram of a dataset is shown in Figure 1. The sample mean is 50. Which one
of the following values for the median is consistent with the histogram? Why?
Median = 48 or Median = 52 or Median = 50.
What is the population and parameter for the following study?.
A study conducted in June, 2016 of 6,138 Australians over the age 'of 14 found'
that 54.7% of them had purchased butter in the preceding 12 months.
Explanation / Answer
Qustion 1.
2 Major issues are
(i) Volunteer bias is there as only volunteer or inspired students are ready for survey. that means the survey will be biased towards such kind of graduaes.
(ii) In second case, the 6 remining students are selected from post graduate students. there are no graduate students and there is no randomness too in selecting these 6 students.
Question 2
where r = -0.9 that means a strong, negative, linear relationhip.
The relationship is strong because value of r is high and near to 1. Negative sign tells that it is a negative relationship. Linearity is a feature of this regression.
Question 3
Population - Australians over the age of 14 who purchaed butter in preceding 12 years
Parameter
N = sample size = 6138
Proportion p = 0.547
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