Observations were made on samples of 10 scalp hairs from each of 20 male undergraduates who were all 20 years of age. The greatest diameters of the hairs were measured proximally just above the hair root and distally 40 mm. away from the root when the hair was dry and wet.It was found that the paired dry proximal and distal measurements could have been a random sample from a bivariate normal distribution. The dry proximal and wet proximal measurements did not fit a bivariate normal distribution until a square root transformation was made on the wet measurements.Analysis of variance of the proximal dry measurements showed that the observations on each subject were not random samples from a homogeneous population. The mean and variance of the observations differed for each subject.In a subsidiary experiment the diameter of the hair shaft was found to be constant for distances up to 40 mm. from the hair root.It was concluded that measurements of hair shaft diameters can be described Dy a multivariate normal distribution for an uncountably infinite number of variables.EVIDENCE is accumulating which implies that malnutrition and other illnesses effect a reduction of hair shaft diameter (Sims, 1968). Biophysical experiments on protein synthesis in the cortical cells of rat anagen follicles have shown that cortical cells synthesize and accumulate proteins at a very rapid rate (Sims, 1964(Sims, , 1966. The matrix cells of the follicle divide about once every 12 hr. and presumably double their mass at the same rate by manufacturing jiroteins and other components. Cortical cells in the mid keratogenous zone of the follicle manufacture proteins about 12 times faster than matrix cells. Depression of the intense anabolic activity of the hair follicle by any factor could result in poor quality protein and a narrow segment of hair shaft being produced during the time the factor ojjerates. A change in the quality of the hair protein is associated with an increase in the amount of swelling that occurs when it is immersed in water.Attempts to associate changes in hair shaft diameters with illness or other factors necessitate a statistical analysis of the observations to exclude the possibility of accepting independent random events as correlated events. These statistical analyses assume that the observations have normal frequency distributions and that the diameter of hair is constant along its length. Usually these assumptions are not tested or challenged and the result of any statistical test is accepted within this limitation. When a continuing programme of work is undertaken, or when similar experiments are performed by a number of people so that repetition of the same assumptions occurs under similar circumstances, it Aocopted for publication January 23rd, 1970.
Observations were made on samples of 10 scalp hairs from each of 20 male undergraduates who were all 20 years of age. The greatest diameters of the hairs were measured proximally just above the hair root and distally 40 mm. away from the root when the hair was dry and wet.It was found that the paired dry proximal and distal measurements could have been a random sample from a bivariate normal distribution. The dry proximal and wet proximal measurements did not fit a bivariate normal distribution until a square root transformation was made on the wet measurements.Analysis of variance of the proximal dry measurements showed that the observations on each subject were not random samples from a homogeneous population. The mean and variance of the observations differed for each subject.In a subsidiary experiment the diameter of the hair shaft was found to be constant for distances up to 40 mm. from the hair root.It was concluded that measurements of hair shaft diameters can be described Dy a multivariate normal distribution for an uncountably infinite number of variables.EVIDENCE is accumulating which implies that malnutrition and other illnesses effect a reduction of hair shaft diameter (Sims, 1968). Biophysical experiments on protein synthesis in the cortical cells of rat anagen follicles have shown that cortical cells synthesize and accumulate proteins at a very rapid rate (Sims, 1964(Sims, , 1966. The matrix cells of the follicle divide about once every 12 hr. and presumably double their mass at the same rate by manufacturing jiroteins and other components. Cortical cells in the mid keratogenous zone of the follicle manufacture proteins about 12 times faster than matrix cells. Depression of the intense anabolic activity of the hair follicle by any factor could result in poor quality protein and a narrow segment of hair shaft being produced during the time the factor ojjerates. A change in the quality of the hair protein is associated with an increase in the amount of swelling that occurs when it is immersed in water.Attempts to associate changes in hair shaft diameters with illness or other factors necessitate a statistical analysis of the observations to exclude the possibility of accepting independent random events as correlated events. These statistical analyses assume that the observations have normal frequency distributions and that the diameter of hair is constant along its length. Usually these assumptions are not tested or challenged and the result of any statistical test is accepted within this limitation. When a continuing programme of work is undertaken, or when similar experiments are performed by a number of people so that repetition of the same assumptions occurs under similar circumstances, it Aocopted for publication January 23rd, 1970.
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