Tuesday, November 02, 2010

Introducing statistics to biologists.

IB Biology topic 1. We are only addressing (training)this criteria so it cannot be used for assessment.

1. Get a box of seeds (I used Copper pod seeds) or any biological material such as snail shells.

2. Split the sample into two. Give them an appropriate name e.g collected from park, collected in school grounds.

3. Ask the students to do an initial qualitative description of the two samples (to be recorded).

4. Student select a dependent variable to measure (or done as a class). e.g. mass

5. Data collection, student record all raw data into an appropriate table (criteria 1) units/uncertainty/ table

6. Introduce the the concept of the central tendency (average) mode, median or mean. Select appropriate average.

7. Since we are measuring on a continuous scale (mass) we will select the mean. Do the calculation. Use graphic calculator or spreadsheet.

8. Find the min/ max  plot the two samples as  the means with min/ max (Excel version perhaps)

9. Introduce the concept of standard deviation, just calculate it / plot it and then discuss the concept.

10. From here you can do visual comparison of the overlap of the mean +/- SD. This is still  based on 'opinion' and will give the opportunity to introduce the idea of a statistical test.

11. The obvious progression is to a stats test, t-test. How to/justification of test choice/ interpretation of answer/ relate to a hypothesis

12. When all of this is finished it does provide an excellent reference point for the future and also a jumping off point for discussion on design.