founder effect

the occurrence of a gene at increased frequency in a group or colony that was initially established by a small number of members of a larger population. The limited number of founders results in limited genetic diversity and a nonrandom genetic sample of the original population. The presence of a founder effect leads to a characteristic genetic makeup, which can allow the tracing of the migration of a particular ethnic group or population over time. Its presence is also associated with the predisposition of some groups to certain diseases. A founder effect has been identified for mutations predisposing to breast cancer among Eastern European Jews, for example.

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Psychology term of the day

November 24th 2024

regression sum of squares

(symbol: SS_regression) a number indicating the amount of variance in a dependent variable that can be explained by the variance in one or more associated independent variables. It thus describes how well a particular model fits the observed data. For example, in linear regression it is used to calculate a coefficient of determination or a coefficient of multiple determination, and in analysis of variance it is used to determine the total sum of squares and calculate an F ratio. Compare error sum of squares.