For each member of your group, write down the total number of "serious" significant others he or she has had:

We are interested in learning about the "typical" number of significant others the population of Stat 250 students has had.  Your group of 4-5 students serves as a sample from the population of all Stat 250 students.

The sample mean  is calculated by adding up the numbers and dividing by the number of data points.  Calculate the sample mean:
 
 
 
 
 

Your sample mean serves as an estimate of the population mean.

Now, the sample median is determined by:

1. Ordering the data from smallest to largest.
2. If the number of data points is odd, the median is the middle value of the ordered data points.
3. If the number of data points is even, the median is the average of the two middle values of the ordered data points.

Your sample median serves as an estimate of the population median.
 
 
 
 
 
 
 
 
 

Now, let's investigate what happens to the sample mean and median when one of the data points is
an outlier, i.e. an extreme observation.  Multiply the largest number in your original data set by 10.  Replace the largest original data point with this new number.  Leave all of the other data points unchanged.  Write down the new data set:
 

Calculate the sample mean of the new data set:
 
 
 
 
 

Calculate the sample median of the new data set:
 
 
 
 
 
 

Write one statement that summarizes how the sample mean and sample median are affected by the presence of an outlier.
 
 
 
 
 

Are the sample mean and sample median sufficient in describing the data?  That is, if you didn't have access to the original data, what else would you like to know about the typical number of serious significant others Stat 250 students have had?