Experiment No. 1: Statistical methods for the analysis of segregation ratio M-6-10-6 Introduction
Statistics is the branch of applied mathematics which deals with collection, preservation, analysis and interpretation of numerical data. Statistics has wide application in the field of physical, biological and social sciences. Fish breeders and geneticist deal with huge data collected on various fish populations. Geneticist and fish breeding are very closely related disciplines. Elementary knowledge of statistics is a pre-requisite for the study of these disciplines. Both geneticist and fish breeders deal with two types of characters viz., qualitative and quantitative characters. The qualitative traits are studied in Mendelian genetics and quantitative genetics are studied in biometrical genetics. For both types of characters the 1 goodness of fit of the numerical result obtained from an actual cross or other experiment relative to predicted results based on a particular mechanism perfect genetics segregation is of important concern. The geneticist must know how much the experimental result can differ from the hypothetical or calculated figure and still be regarded as the result of expectation. The best geneticist can do it to determine the deviation occurring by chance and use this statistical inference to decide whether a particular results support the given hypothesis. The various statistical procedures and concepts which are used for the analysis of qualitative and quantitative characters are briefly described.
Probability
The term probabilities is defined as the number of times a particular events occurs, divided by the total number of opportunities for the event to occur. For example, if a coin is flipped ten times and turns up heads four times and tails six times, the observed probabilities of heads in these ten tosses is 4/10 - 04 and the observed probabilities of tails is 6/10 -0.6. The sum of these probabilities is unity: that is, 4/10 6/10 1. If the coin is "fair" that is, equally likely to land on heads and tails and if it is flipped many times, the expected probabilities are 0.5 for heads and 0.5 for tails.
X2test
A statistical test to determine if the observed numbers deviate from those expected under a particular hypothesis. The main principle of chi-square test is the frequencies we observe are compared with those expect on the basis of some null hypothesis. This is a statistical test used to test the significance of difference between observed and expected frequencies or ratios.
Principles of Genetics (P-1)
If the discrepancy between observed and expected frequencies is great then the value of the calculating test statistic will exceed the critical value at the appropriate degrees of freedom. We are then obliged to reject the null hypothesis in favor of any alternatives.
Karl Pearson, an English mathematician applied statistics to biological problems of heredity and
evolution. He developed the Chi-square test (commonly known as ) of significance which is commonly used in Mendelian and population geneties. The general formula of is as follows
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with (n-1) degree of freedom
Wh
Favorite Expected fro Edit
O-Observed frequency
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O-E-Difference between observed and expected frequencies
Total number of observation
E-Summation
This application 8 mins onerve frequenters and expired fequencies The experiet
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