Introduction to Statistics
Checkpoints on this Page:
Let’s Use Statistics!
Sample Dataset For Examples Below
1, 2, 6, 5, 1
Measures of Center
The measures of center tell us about what is typical in a group of numbers. A set of numbers has different kinds of centers: a mean, a median, and a mode. Sometimes these measures will have the same value and sometimes they will be different. We calculate them in different ways.
Mean
The mean is often called the “average”. To find the mean, we add up all of the numbers of interest and divide by how many numbers there are.
\(\LARGE \frac{1 + 2 + 6 + 5 + 1}{5} = 3\)
The mean value of this sample dataset is 3.
Median
The median is a different kind of measure of center. To calculate the median, you first line up all the values in your data set, then you find the middle value by position.
\(\Large 1 + 1 + 2 + 5 + 6\)
The median value of this sample dataset is 2.
Let’s Analyze Your Lab Data
Get your calculator ready!
On your lab sheet, you have the nitrate and nitrite concentrations for each sample. Then, to the right, you have space to perform some statistical analyses and calculations.
- Calculate mean nitrate concentration
- Calculate mean nitrite concentration
- Calculate median nitrate concentration
- Calculate median nitrite concentration
RECORD THESE ON YOUR LAB SHEET