Exam 3: Describing Data Visually

Below is a frequency distribution of earnings of 50 contractors in a country. Earnings Number of (thousands) Contractors 1-10 2 11-20 7 20-30 12 31-40 15 41-50 8 50-60 6 Regarding this distribution, which of the following is correct?

Briefly list strengths and weaknesses of this display. Cite specific principles of good graphs, as well as offering your own general interpretation.

A column chart would be least suitable to display which data?

In a bimodal histogram, the two highest bars will have the same height.

Dot plots may not reveal the shape of a distribution when the sample is small.

Below is a sorted stem-and-leaf diagram for the measured speeds (miles per hour) of 49 randomly chosen vehicles on highway I-80 in Nebraska. What is the mode? stem unit $=10$ leaf unit $=1$ Frequency Stem Leaf 1 4 9 1 5 5 17 6 01222455556688999 19 7 0111233345666778999 7 8 0133557 4 9 0122 49

Which data would be suitable for a pie chart?

A histogram can be defined as:

A scatter plot is useful in visualizing trends over time.

A study found the following parts per billion of nitrosamines in a sample of domestic beers. (a) Construct a frequency distribution of four classes with equal class sizes. (b) Construct another frequency distribution of four classes using unequal class intervals or an open-ended interval for the highest class. (c) Which frequency distribution is preferable? Why? 1.00 1.72 2.51 4.21 1.05 1.88 2.61 4.50 1.17 2.16 2.84 6.36 1.50 2.23 2.96 6.70 1.63 2.26 2.99 6.72 1.70 2.45 3.41 15.75

Briefly list strengths and weaknesses of this display. Cite specific principles of good graphs, as well as offering your own general interpretation.

Ten part-time servers at a high-end restaurant were asked how many hours they worked last week and how much they earned. The results are shown below. (a) Make a scatter plot. (b) Describe it. (c) What is your best guess of the average hourly pay? Work Hours Last Week's Pay 5 75 7 70 10 150 15 195 21 210 25 350 33 495 35 315 40 320 45 495

The number of bins in this histogram (caffeine content in mg/oz for 65 soft drinks) is consistent with Sturges' Rule.

If you have 256 data points, how many classes (bins) would Sturges' Rule suggest?

Bob found an error in the following frequency distribution. What is it? Class Frequency 1-10 2 11-20 6 25-30 8 31-40 12 44-50 6

A column chart can sometimes be used instead of a line chart for time series data.

Pivot tables:

The width of a class in a frequency distribution is known as the:

Scatter plots are used to visualize association in samples of paired data (X, Y).

The column chart should be avoided if you are plotting time series data.