Statistical inference by normal probability paper

It is difficult to discuss the distribution visually when the size of sample is small. In this case, histogram is not useful, so that normal probability paper (N.P.P.) is often used. However, it has bias in the point estimation of standard deviation though there is no abnormal data. If abnormal data exists, then it has serious influence in the statistical inference of mean and standard deviation. This paper proposes new methods of N.P.P. for small sample. Proposed method is to get the unbiased estimation of standard deviation for the case without abnormal data and the case with abnormal data. Coefficients for new methods are prepared.