BIOL 3327 Experimental Methods

Flashcards based on key concepts from the BIOL 3327 lecture notes, focusing on t-tests and ANOVA.

What complication arises when performing a t-test with populations that have different variances?

Calculating degrees of freedom, where the population with the largest variance dominates the degrees of freedom.

What is a key feature of a paired t-test?

It compares the differences between paired data points from the same species rather than individual observations.

What formula is used to calculate the F statistic in ANOVA?

F = MST/MSE, where MST is the mean sum of squares due to treatment and MSE is the mean sum of squares due to error.

What does a high F-ratio in ANOVA indicate?

It suggests that treatment variance is significantly larger than background variance.

How does the t-test handle variations in sample size?

The t-test accounts for finite and different sample sizes and allows for broader confidence limits as sample size decreases.

In a paired t-test comparing two soils, what are the degrees of freedom (df) if there are 10 differences?

The degrees of freedom is 9 (n-1) for the paired t-test.

What outcome indicates that a paired t-test is more sensitive than an unpaired t-test?

The paired t-test may show significant results when the unpaired test accepts the null hypothesis, indicating a false negative in the unpaired test.

What is the relationship between sample size and variance estimation in the t-test?

The smaller the sample size, the worse the variance estimate, which can lead to Type 1 errors (false claims of difference).

What kind of statistical test is ANOVA, and when is it used?

ANOVA is used to analyze variance among three or more groups to assess relationships between dependent and independent variables.

What defines a successful grouping of a population in data analysis?

Homogeneous groups with low variance and distinct means for each group.