1.5 Data Collection Experiment

1.5.1 Stats Lab: Data Collection Experiment

This section is a hands-on lab, not a reading. You'll go gather real data, sort it into tables, and then see how the way you group numbers can change the story they tell. Work through it with your class.

Class Time:

Names:

1.5.2 Student Learning Outcomes

By the end of this lab, you should be able to:

Demonstrate the systematic sampling technique (the "pick someone, then count down a fixed number of names" method).
Construct relative frequency tables from raw data.
Interpret your results and explain why different ways of grouping the same data can lead to different-looking answers.

1.5.3 Movie Survey

Ask five classmates from a different class how many movies they saw at the theater last month. Do not include rented movies.

Record the data.
In class, randomly pick one person. On the class list, mark that person's name. Move down four names on the class list. Mark that person's name. Continue doing this until you have marked 12 names. You may need to go back to the start of the list. For each marked name record the five data values. You now have a total of 60 data values.
For each name marked, record the data.

1.5.4 Order the Data

Complete the two relative frequency tables below using your class data.

Step 2 is systematic sampling in action. Instead of grabbing names at random one by one, you start at one random spot and then step through the list at a fixed interval (every 4th name). It's like picking every 10th house on a street — easy to do, and it spreads your sample evenly across the whole list.

**Table 1.5.1** — Frequency of Number of Movies Viewed.
Number of Movies	Frequency	Relative Frequency	Cumulative Relative Frequency
0
1
2
3
4
5
6
7+

**Table 1.5.2** — Frequency of Number of Movies Viewed.
Number of Movies	Frequency	Relative Frequency	Cumulative Relative Frequency
0–1
2–3
4–5
6–7+

Now use your completed tables to answer these:

Using the tables, find the percent of data that is at most two. Which table did you use and why?
Using the tables, find the percent of data that is at most three. Which table did you use and why?
Using the tables, find the percent of data that is more than two. Which table did you use and why?
Using the tables, find the percent of data that is more than three. Which table did you use and why?

1.5.5 Discussion Questions

Is one of the tables "more correct" than the other? Why or why not?
In general, how could you group the data differently? Are there any advantages to either way of grouping the data?
Why did you switch between tables, if you did, when answering the question above?