Chi squared summary notes
28 February 2023 12:42
Null hypothesis (H0)- no statistically significant difference between the phenotypes we obse
phenotypes we expect (example for phenotypes)
Alternative hypothesis (H1)- there is a significant difference between observed and expected
- State each hypothesis (apply to question)
- Obtain expected and observed results for experiment
- Calculate difference
- Square each difference
- Divide each squared difference by expected value
- Sum these answers
Analysing chi squared values
- Critical table value required
- If the chi squared value is larger than critical- differences between expected and obser
significantly different from expected results- accept H1
- Smaller value than critical- results due to chance - accept H0
- Generally 0.05 probability - 5% probability the difference in the results we observe and
due to chance
- Degrees of freedom- the number of comparisons made when determining critical prob
categories - 1)
Example
28 February 2023 12:42
Null hypothesis (H0)- no statistically significant difference between the phenotypes we obse
phenotypes we expect (example for phenotypes)
Alternative hypothesis (H1)- there is a significant difference between observed and expected
- State each hypothesis (apply to question)
- Obtain expected and observed results for experiment
- Calculate difference
- Square each difference
- Divide each squared difference by expected value
- Sum these answers
Analysing chi squared values
- Critical table value required
- If the chi squared value is larger than critical- differences between expected and obser
significantly different from expected results- accept H1
- Smaller value than critical- results due to chance - accept H0
- Generally 0.05 probability - 5% probability the difference in the results we observe and
due to chance
- Degrees of freedom- the number of comparisons made when determining critical prob
categories - 1)
Example
