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Biostatistics in biology. Why we use biostatistics in biology.

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Presentation on theme: "Biostatistics in biology. Why we use biostatistics in biology."— Presentation transcript:

1 Biostatistics in biology

2 Why we use biostatistics in biology

3 Facts should be proven e.g. Chemical A is anticancer drug. How to prove it?

4 Facts should be proven e.g. Chemical A is anticancer drug. How to prove it? Experimental design Experimental factors Control

5 Experimental design Measure for a pre-tested parameters such as markers Use prop Test Analysis ……..etc.

6 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

7 Sample size Number of replicates tested

8 Control Positive control Negative control

9 Where is the correct value? variable R1: 30 R2: 26 R3: 36 R4: 48 R5: 50 R6: 16 R7: 31 Mean(Ý) =33.85 n=7

10 Statistical analysis

11

12 Standard deviation Degree of freedom =n-1

13 Biological data Aflatoxin in peanut ( Y) Y-Ý(Y-Ý) 2 303.8514.822 267.8561.622 36 48 50 16 31 Mean(Ý) =33.85 n=7 =

14 Justify a genetic hypothesis using chi square test

15 Chi square test X2 = Also called ANOVA or X 2 test for goodness of fit Is observed data consistent with hypothesized ones?

16

17 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.

18 Problem 1 Justify 3:1 ratio

19 Problem 2 Do you think the inheritance of the above genetic trait follows the ratio of 1:2:1

20 Problem 2 answer justify the ratio 1:2:1 GenotypeobservedexpectedO-E AA159159.75-0.750.003 Aa321319.51.50.007 aa159159.75-0.750.003 Total6390.013

21 Types of variables 1- Qualitative 2- Quantitative

22 Arrange your data in a meaningful form 1- Data tabulation 2- Graph 3-Statistical analysis

23

24 Use of molecular genetic in genotyping

25 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

26 Mutation induction to study a genetic trait X-ray Insertional mutagenesis Chemical mutagenesis

27 Complementation test in gene identification

28 Results interpretation


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