Data

• Have students collect data about topics of interest to them. Data they gather themselves is usually more interesting to them.

• Be sure students arrange the data in either ascending or descending order before seeking to find the median. Finding the middle point before ordering the data is a common mistake.

• One way to physically see the median is to order the data and then remove one number from each end of the data until you reach the middle number or middle two numbers.

• When all your outliers are greater than the other data points, the mean is greater than it would be without those outliers. Similarly, if all the outliers are less than the other values, the mean is less than it would be without those outliers.

• When you encounter an outlier, it is good to re-examine that data item to see if a mistake occurred or to see if you can explain why the outlier occurred.

• A common mistake made when collecting information about a population is to collect it from a subset of the population and claim it reflects the total population. For example, when collecting data about how the general population feels about animal shelters, a sample from people who work at animal shelters would be biased.
Measures of Central Tendency:
Mean, Median, and Mode

Sampling Techniques