Question

Suggest an experiment to test the hypothesis that low 2D/4D ratio correlates to an increased risk of developing male pattern baldness.

Answer 1

The ratio between 2nd digit (index finger = 2D) to the 4th digit (ring finger = 4D) length has been hypothesized to reflect the disease condition and the sensitivity of the individual. In male 4D is longer than 2D. Information needed regarding whether the 2D:4D ratio is correlated with the disease or not. To test the hypothesis collect patients affected with baldness (excluding the patients who have taken drug or any other chemical which can affect the hair follicle growth in the preceding three months, also exclude the patients who undergone a hair transplantation treatment).

Baldness severity can be assessed with the help of Hamilton-Norwood (HN) scale and Finger-lengths can be measured with the help of digital vernier calliper with a resolution of 0.01 mm. Ring and index fingers measured on the palmar surface of both hands from basal crease to tip. In case detecting more than one fold at the base of finger, the most proximal fold was used. 2D:4D ratio can be calculated by dividing the length of index finger by the length of the ring finger.

To analyse differences between groups Student’s t-test can be used when normality of variable distribution was acceptable. To measure the degree of the difference in 2D:4D between individuals with baldness and control Cohen’s effect size need to be calculated. Use Spearman correlation coefficients to examine relationships between digit ratios and baldness severity. P<0.05 in case of two tailed   test can be considered as significant.