Facts should be proven
e.g.
• Chemical A is anticancer drug.
• How to prove it?
• Experimental design
• Experimental factors
• Control
Experimental design
• Measure for a pre-tested parameters such as markers
• Use prop
• Test Analysis ……..etc.
Experimental factors
• All experimental factors should be fixed except the drug
• E.g. Dose dependant
• Different extraction method of the drug
• Different administration of the drug
• Sample size of the experiment
Biological dataAflatoxin in peanut ( Y)
Y-Ý (Y-Ý)2
30 3.85 14.822
26 7.85 61.622
36
48
50
16
31
Mean(Ý) =33.85
n=7
=
Chi square test
• X2 =
• Also called ANOVA or X2 test for goodness of fit
Is observed data consistent with hypothesized ones?
Example for chi square test application in genetics
In a cross between smooth and wrinkled pea seeds, you obtained 99
smooth seeds and 45 wrinkled seeds. Determine if the ratio 3:1 is
consistent with this result.
Problem 1
Phenotype Observed number Expected number Deviation from expected number
Wild type 99 108 -9 0.75 Mutant 45 36 +9 2.25 Totals 144 144 0 X2=3
Justify 3:1 ratio
Problem 2 answerjustify the ratio 1:2:1
Genotype observed expected O-E
AA 159 159.75 -0.75 0.003
Aa 321 319.5 1.5 0.007
aa 159 159.75 -0.75 0.003
Total 639 0.013
Genetic analysis
• Analysis of a certain genetic trait is very complicated.
• Researchers need to identify all genes responsible for phenotype determination as well as interacting genes.
• E.g.
• Cell shape genes and mutation induction methodology
Mutation induction to study a genetic trait
• X-ray
• Insertional mutagenesis
• Chemical mutagenesis