EBook Problems EDA Shape

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EBook Problems Set - Measures of Shape

Problem 1

46% of the likely voters in Los Angeles intend to vote for Mayor James. Suppose we take a random sample of 1000 likely Los Angeles voters. For every person in our sample who intends to vote for Mayor James we will record a "1". For every person who will not vote for the mayor, we will record a "0". Suppose we now make a histogram of our results. Which of the following is a good description of the histogram?

  • Choose one answer.
(a) The distribution will have a spike at the value 0.46
(b) The distribution will be approximately normal
(c) The sample size is too small to tell
(d) The distribution will show about 46% of the replies at 1 and 54% at 0

Problem 2

The Old Faithful Geiser in Yellowstone, Wyoming, erupts pretty regularly. After an eruption has occurred, one has to wait for the next eruption for some time. The waiting time has a histogram with two peaks or bumps (bimodal): one peak in the lower end and one in the upper end, with very little frequency in between. What does this suggest about the waiting time?

  • Choose one answer.
(a) The waiting time does not depends on how long the last eruption was
(b) The waiting time should have been plotted with a bar graph, not a histogram
(c) There are two groups of waiting times, and in order to study this variable, we should analyze each group separately

Problem 3

From what kinds of variables sould a histogram be generated?

  • Choose one answer.
(a) Quantitative only
(b) Categorical only
(c) Varies according to situation
(d) One categorical and one quantitative

Problem 4

Imagine that students find a recent 10 point quiz very easy and almost all do very well. Describe the shape of distribution of scores when you plot the scores on this quiz.

  • Choose one answer.
(a) The distribution of scores is skewed left since some students did not do well.
(b) The distribution of scores is bimodal since some students did well and some did not.
(c) The distribution of scores is nearly normal since quiz grades are curved.
(d) It is not possible to describe the shape of the distribution unless you have the actual values.
(e) The distribution of scores is skewed right since some students did not do well.

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