Tutorial Letter 201/0/2023
Descriptive Statistics and Probability
STA1501
Year module Department of
... [Show More] Statistics
PART A: 20 Marks (1 mark each)
QUESTION 1
False. A qualitative variable for which there is some kind of ranking for the different values is called an ordinal variable.
QUESTION 2
False. Samples in which the elements to be selected are drawn on the basis of probabilities in such a way that each element in the population has the same probability of being selected as part of the sample are called simple random samples. These fall under under probability sampling methods, but there are others.
QUESTION 3
True. Each individual data value is split into a stem and leaf. For example, suppose there exist individual data values as follows:
150, 155, 156, 200, 218, 211, and 216.
Then the stem-and-leaf display is
Stem Leaf
15 0 5 6
20 0
21 1 6 8
and from this, all of the original data valus can be read out.
QUESTION 4
False. This would be an example of a statistic.
QUESTION 5
False. A histogram is used to summarise only quantitative data.
QUESTION 6
False. The interquartile range tells us the spread of the middle half of a dataset, whereas; the range tells the spread of the entire dataset. The length of the first does not have to be half of the second, that depends entirely on how the data is spread around.
QUESTION 7
False.
QUESTION 8
False. Increasing the sample size has a property of making the sample statistic less variable. This has no influence on survey bias and thus a large sample size does not correct methodological problems (i.e., bias, undercoverage and etc.).
QUESTION 9
True, since b0 5.2 and b1 0.3. If b1 < 0, then x and y have a negative relationship, and otherwise if b1 > 0, then x and y have a positive relationship.
QUESTION 10
False. Since r Sxy , then S can be smaller or greater than r.
Sy Sx
QUESTION 11
QUESTION 12
QUESTION 13
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