This is a presentation for my Env. Chem students regarding the basic statistics they will be using in class throughout the year.

1. Basic Descriptive
Statistics
Mr. Siko
Clarkston HS

2. Why?
 Descriptive statistics do just that:
Describe Data!
 What we’ll cover in this slidecast
– Mean (average)
– Median
– Mode
– Range

3. Mean
 Fancy Formula  What this means: add
µ = ΣX/N up all your data, then
divide by the number
of data points

4. Mean
Sample data: How to calculate:
98cm
76cm 98+76+82+54+90 =
82cm 400cm
54cm
90cm 400cm/5 = 80cm

5. Median
 The median is the middle data point in a
set
 To determine the median, sort the data
from smallest to largest and find the
middle data point

6. Median
Sample data: Rearranged Data:
98cm 54cm
76cm 76cm
82cm 82cm
54cm 90cm
90cm 98cm

7. Median
 If there is an even number of data, there
will be two middle points.
 To find the median, take the average of
those two data.

8. Median
Sample Data: Rearranged Data:
4ml 2ml
8ml 4ml
12ml 8ml
2ml 12ml
4 + 8 = 12ml
12/2 = 6ml

9. Mode
 The mode is the most frequently occurring
data point.
 To find the mode, arrange the data from
smallest to largest, and then determine
which amount occurs most often.

10. Mode
Sample Data: Rearranged Data:
20g 23g 20g 20g 20g
30g 30g 22g
22g 27g 23g 23g 23g 23g
25g 20g 24g
23g 24g 25g 25g
23g 25g 27g
20g 23g 30g 30g

11. Range
 The range is the distance between the
smallest and largest data point.
 To calculate, determine the smallest data
point and the largest data point, then
subtract the smallest from the largest.

12. Range
Sample data: Rearranged Data:
98cm 54cm
76cm 76cm
82cm 82cm
54cm 90cm
90cm 98cm
98cm – 54cm = 44cm

13. Recap
 Mean, Median, Mode, and Range
“describe” the data.

14. Acknowledgements
American Chemical Society. (2006).
Chemistry in the community: ChemCom
(5th ed). New York: W.H. Freeman