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5.7 Calculation of corrected segregation ratio according to Singles method

The method is to be used when your data are collected in the field, and
you only find useful families where at least one affected offspring occur.
Put your data in the second line and press the **Calculate**
button.

Example:

The disease tyrosinemia in mink is investigated by the following set
of field data for recessive Mendelian inheritance. A description of the
disease tyrosinemia in mink are published by Christensen et al. Canadian
J. Comparative Medicine, 43:333-340, 1979.
In the data set 16 litters are included with at least one affected offspring.
The observed numbers are given below.

T = 94 - total numbers of pups
A = 32 - total number of affected
A_{1} = 4 - number of families with one affected pup
A_{2} = 9 - number of families with two affected pups

The applied formulas for test of Mendelian inheritance by "Singles method"
(with the proportion p-hat ) are shown in the figure below. The tyrosinemia data
are applied to show the use of the formulas. The results below are rounded, so they
are sligthly different from what you get using the above calculator.
The Z^{2} are Chi-squared distributed with 1 degree of freedom.
The test of p-hat is against 0,25, this is the expected ratio when both
parents are carrier and there is recessive inheritance. The test value
is less than 3.84. Therefore the deviations can be accepted as not statistically
significant.

Questions:

Calculate the corrected segregation ratio for the following observation set of field
data, where there has been at least one affected per family.
T = 30 - total numbers of observations
A = 16 - total number of affected
A_{1} = 12 - number of families with one affected
A_{2} = 2 - number of families with two affected

Is the segregation ratio statistically significant different from 1:3 segregation.

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