Crossbill finches have beaks that overlap with the top beak to one side or the other of the lower beak. Most populations have 50:50 ratios of "right-handed" and "left-handed" beaks, and the handedness of the beaks is thought to be randomly determined, so we expect to see equal numbers of right-beak and left-beak finches. Consider a survey of 140 crossbill finches, which reveals 82 with right beaks and 58 with left beaks. What is the conclusion of a two-sided binomial test using the normal distribution to approximate the binomial?

Question

Quizplus · Accepted Answer

The null hypothesis in this context posits that the distribution of beak handedness is random, implying a 50:50 ratio between right-beaked and left-beaked finches. The observation of 82 right-beaked and 58 left-beaked finches in a sample of 140, while showing a deviation from the expected 50:50 ratio, may not be statistically significant enough to reject the null hypothesis when subjected to a two-sided binomial test using the normal distribution approximation. Therefore, without further statistical details provided, the most appropriate conclusion is that we fail to reject the null hypothesis, indicating a lack of evidence to suggest that the handedness of the beaks is non-random.

Crossbill Finches Have Beaks That Overlap with the Top Beak