Mendelian Genetics and Chi-Square Test

Flashcards covering key vocabulary related to applying statistical tests, specifically the chi-square test, to evaluate Mendelian principles in genetics.

Statistical Test

A method used to determine if observed offspring ratios are significantly different from predictions based on Mendel's principles, or if differences are due to random chance.

Null Hypothesis

A statement in a statistical test that assumes no significant difference between observed and expected values, often based on Mendelian predictions.

Critical Value

A predetermined threshold in a statistical test (like the chi-square test) used to decide whether to reject or fail to reject the null hypothesis.

Chi-Square Test (χ²)

A statistical test statistic used to assess the 'goodness of fit' between observed data and expected values, particularly in Mendelian genetics to see how well observed data fits expected phenotypic ratios.

Goodness of Fit

A statistical measure, often evaluated by a chi-square test, indicating how well an observed distribution of data matches an expected distribution.

Observed Number

The actual count of individuals for a specific genotype or phenotype present in an experiment's results.

Expected Number

The predicted count of individuals for a specific genotype or phenotype, calculated based on Mendelian principles (ratios, fractions, or percentages).

Chi-Square Value Calculation

Calculated as the sum of [(observed number - expected number)² / expected number] for each phenotypic class.

Degrees of Freedom (df)

A parameter used in statistical tests, calculated as the number of phenotypic classes minus one, which helps determine the appropriate critical value from a chi-square table.

P-value (p = 0.05)

A probability threshold, typically set at 5% (0.05), which indicates that if the calculated test statistic falls within this extreme percentage of the distribution, the observed differences are considered statistically significant and likely not due to chance.