Various techniques and equipment may be employed for the calculation of odor thresholds. An average odor threshold value can be ascertained by examining the distribution of relative sensitivity to a specific chemical odorant across a large population. It is important to recognize that although this final result may appear as a single threshold value or an estimated range of values with accompanying confidence limits, it is based on a substantial amount of underlying experimental tests. Inherent variability and response bias are unavoidable factors in olfactory perception studies. Even within the same panel, individual responses can vary significantly-ranging from a two-fold to a four-fold difference in the same experiment . Interpersonal variability can be even more pronounced, with differences sometimes escalating to as much as three orders of magnitude .