Introduction
In this activity you will compare the length of missions for four space shuttles over a seven-year period. You will determine statistical measures of central tendency, including mean, median, and mode. You will also create a box-and-whiskers plot. You will draw the upper and lower quartiles and show the upper and lower end points of the data on your graph. These skills will be important during the mission.

Vocabulary

box-and-whiskers plot: a method of displaying data that helps in interpreting how data is distributed on an interval scale. A box-and-whiskers plot shows the shape of the distribution, its central value, and the variability. It especially helps show whether a distribution is skewed or whether there are unusual observations in the dataset (outliers).

central tendency: how much the values of a distribution cluster, usually measured by mean, median, or mode.

lower quartile: the median of the lower part of the data.

mean: the arithmetic average; the sum of all the scores divided by the number of the scores.

median: the middle of a set of data. Half the scores are above the median; half are below. To find the median:

• If the number of data is odd, the median is in the center.
• If the number of data is even, the median is the average of the two center scores.

mode: the number or score that appears most often in a set of data.

quartile: a division or group of data that separates the data into equal parts.

upper quartile: the median of the upper part of data.

• Data Analysis worksheet
• Pencil
• Ruler

1. Be sure you understand all of the vocabulary. 
2. Look at the Atlantis data example. Use this example to guide you as you create a box-and-whiskers plot for the other three shuttles’ data.
3. Analyze the mean, median, mode, and box-and-whisker plot for each shuttle to answer the questions.

The following table contains data from space shuttle missions flown from 1996-2003.

Tasks

• Construct box-and-whiskers plots for each of the space shuttles and the durations of its missions. 
• Identify the mean, median, and mode for each of the four sets of data.
• An example has been done using the Atlantis data. Use this example as a model to construct a box and whiskers plot and identify the mean, median, and mode (central tendencies) for the other shuttles.

10, 9, 10, 12, 9, 12, 11, 10, 10

Step 1: Calculate the Mean

Mean = (10+9+10+12+9+12+11+10+10)/9
Mean = 10.33

Step 2: Calculate the Median
There are nine numbers in the set of data. The median is the one in the middle when they are written in ascending numerical order:

9, 9, 10, 10, 10, 10, 11, 12, 12
Median = 10

Step 3: Calculate the Mode
List how many times each number is repeated:

Number	Repetitions
9	Two
10	Four
11	One
12	Two

Mode = 10

Step 4: Draw the Box-and-whiskers Plot
Find the lower quartile, the median, the upper quartile, the smallest value, and the largest value.

Smallest ↓				Median ↓				Largest ↓
9	9	10	10	10	10	11	12	12
		↑ Lower quartile				↑ Upper quartile

b)      Graph those values in the worksheet. Draw a box between the two quartiles.

Data Analysis Worksheet
In the following worksheet construct box-and-whiskers plots and identify the mean, median, and mode for each of the shuttles.

Analysis Questions
Use your box-and-whiskers plots to answer the following questions:

1. Which shuttle flew the longest mission? 

    

    

    

2. Which shuttle flew the shortest mission?

    

    

    

3. Which shuttle’s duration had the smallest range? Explain. 

    

    

    

4. Which shuttle had a median of 11 days?