## Saturday, 15 September 2012

### Deconvoluting a genetics question (branch diagram solution)

One of the common tasks for a genetics student is to break down a complex question and solve it systematically. Here's the kind of question I often put on an exam. There are several ways to solve it; I include one that uses a branch diagram to find the answer.

## Wednesday, 12 September 2012

###
The theory behind the Chi^{2} test

Most textbooks do a pretty bad job in describing how the Chi

The Chi

^{2}test works and how to apply it.
Here's my first video on the subject. It goes into the theory behind the Chi

^{2 }formula and when you would apply the statistic to your data. The components of the Chi^{2}formula are discussed so you should be able to get an idea what it measures.The Chi

^{2}test is commonly taught in Genetics courses to give students a tool to assess whether data could belong to particular ratios (

*e.g.*3:1, 1:2:1, 9:3:3:1). After viewing this video, you should:

- recognize that the Chi
^{2}formula measures deviation of and observed value from a theoretical value for purposes of comparison - be able to calculate the Chi
^{2}score from a set of data - determine the degrees of freedom for a particular sample
- be able to reject or fail to reject a set of data from a theoretical population by using the Chi
^{2}table

Actually

*doing*the Chi^{2 }test is quite simple. I'll provide a few examples of calculating the Chi^{2}value and interpreting it using the Chi^{2 }table.
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