The proposed study design is one in which for each one of the three specific aims described above, there is one dependent variable (outcome) and 1 independent variable (2 independent populations: subjects with seborrheic dermatitis and scalp itch and controls without scalp itch or seborrheic dermatitis). For non-normal data, we intend to use a non-parametric test, such as the Mann Whitney or Wilcoxon rank sum test to assess for statistical differences between the medians between these populations. In addition, we will use non-parametric analysis, such as the Spearman correlation to correlate results of the skin testing with results of the immunohistochemical counts of nerves. If in fact distributional assumptions are met to allow parameteric analysis, we will use a 2 independent sample t-test to assess for statistical differences between the means.