The mean is the average you're used to, where you add up all the numbers and then divide by the number of numbers. The median is the middle value in the list of numbers. To find the median, your numbers have to be listed in numerical order, so you may have to rewrite your list first. The mode is the value that occurs most often. If no number is repeated, then there is no mode for the list. The range is just the difference between the largest and smallest values.
http://www.purplemath.com/modules/meanmode.htm
We use statistics such as the mean, median and mode to obtain information about a population from our sample set of observed values. The median of a set of data values is the middle value of the data set when it has been arranged in ascending order. That is, from the smallest value to the highest value. The mode of a set of data values is the value(s) that occurs most often.
http://www.mathsteacher.com.au/year8/ch17_stat/02_mean/mean.htm
To clear the calculator and enter a new data set, press Reset. What is the median The median is a measure of central tendency. It represents the value for which 50% of observations a lower and 50% are higher. Put simply, it is the value at the center of the sorted observations.
http://www.alcula.com/calculators/statistics/median/
The median is the middle value. In a list of ten values, that will be the (10 + 1) ÷ 2 = 5.5 th value; that is, I'll need to average the fifth and sixth numbers to find the median: (10 + 11) ÷ 2 = 21 ÷ 2 = 10.5. The mode is the number repeated most often.
http://www.purplemath.com/modules/meanmode.htm
Analysing Data. The mean, median and mode of a data set are collectively known as measures of central tendency as these three measures focus on where the data is centred or clustered. To analyse data using the mean, median and mode, we need to use the most appropriate measure of central tendency.
http://www.mathsteacher.com.au/year8/ch17_stat/02_mean/mean.htm
Outliers are values that  lie out side the other values. A new coach has been working with the Long Jump team this month, and the athletes' performance has changed.
http://www.mathsisfun.com/data/outliers.html
When you think of the mean of a data set, think of the word average. 'Mean' and 'average' are the same thing when you're talking about a set of data! This tutorial introduces you to mean and shows you how to find it!
http://www.virtualnerd.com/middle-math/probability-statistics/mean-median-mode-range/mean-data-set-definition
Median Calculator Instructions This calculator computes the median from a data set: To calculate the median from a set of values, enter the observed values in the box above. Values must be numeric and may be separated by commas, spaces or new-line. You may also copy and paste data into the text box.
http://www.alcula.com/calculators/statistics/median/
The mode and median didn't change very much. They also stayed around where most of the data is. So it seems that outliers have the biggest effect on the mean, and not so much on the median or mode. Hint: calculate the median and mode when you have outliers.
http://www.mathsisfun.com/data/outliers.html
So it is a good idea in this case to remove Sam's result. When we remove outliers we are changing the data, it is no longer pure, so we shouldn't just get rid of the outliers without a good reason! And when we do get rid of them, we should explain what we are doing and why.
http://www.mathsisfun.com/data/outliers.html
what is median of a data set
The median of a data set is a measure of central tendency as it focuses on where the data is centered or clustered.