1. A study is conducted to determine if the traffic light patterns at a busy intersection need to be
adjusted to help the flow of traffic. Data on the volume of traffic and the traffic patterns during
different times of day are recorded.
I. What is the population?
II. What is the sample?
III. Is the study observational or experimental? Justify your answer.
IV. If observational, identify ALL variables. If experimental, identify ALL independent and
V. For each of the variables identified in part IV, list which of the four levels/scales of
measurement was used to obtain data on these variables?
VI. Classify each of the variables identified in part IV as either attribute or numerical.
I . Total Flow of the Traffic
II. The volume of Traffic & the patterns that are recorded.
III. It is an experimental study because the objective is to make changes and see how those
changes are effective and evaluate them. Since we are not merely drawing conclusions, it is not
IV. Variables are
1. Volume of traffic
2. Number of Vehicles
V. Volume of traffic – Ratio
Number of Vehicles – Ratio
Time – Nominal
2. Classify the following variable as nominal, ordinal, discrete, or continuous and state why
it is such a variable:
number of MP3 players sold each year
This is a discrete variable because there cannot be a value in decimals here.
3. Classify the following as an example of a nominal, ordinal, interval, or ratio level of
measurement, and state why it represents this level:
distance between two signposts
The distance between the signposts is a ratio level of measurement, because there is a set
definition of 0.0, as in no distance between these signposts. This has all the properties of an
interval variable and has a well defined value of 0.0, therefore such an example is a ratio level of
4. Construct a frequency distribution table to organize the following set of data:
5. Construct a grouped frequency distribution for the following 28 scores using a class width of
74 80 79 74 77 64 77 81 63 68 83 71 75 71
70 69 83 71 82 86 77 86 79 75 81 86 78 77
6. Provide a different example for each of the following types of variables from your work or
A) A qualitative variable:
A qualitative variable could be the degree of honesty in each of my students during a
B) A quantitative variable
A quantitative variable could be “height” for each of these students.
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