Statistical inference by normal probability paper

A method is described of plotting deoxyribonucleic acid (DNA) thermal melting data which allows information other than average content of guanine plus cytosine to be determined. Absorbancy (A) values, corrected for thermal expansion, are plotted on normal probability graph paper and the best straight line drawn. The 50 percentile point on the graph establishes the Tm value which allows calculation of the mean base composition. In addition the 2σ (twice the standard deviation) value is easily determined from the probability plot, thus providing information about the degree of variation from the mean in DNA base composition. Comparison of the probability plot and usual graphic methods of determining Tm values provided similar DNA composition data on 15 different strains of Streptococcus lactis, Streptococcus cremoris, and Streptococcus diacetilactis. When many A values obtained from streptococcal DNA samples showing skewed thermal melting curves (S. lactis b and S. diacetilactis DRC-2) were plotted on normal probability paper, two intersecting straight lines were apparent on the graph. This suggested that there were two types of DNA in these organisms. Each had its own unimodal compositional distribution and its presence was confirmed by density gradient separation. The use of normal probability plots as a rapid method of determining average base composition of DNA samples is suggested. In addition, heterogeneity in base composition may be shown by this method of plotting the data.

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Use of Normal Probability Paper

Journal of the American Statistical Association ◽

10.1080/01621459.1954.10501234 ◽

1954 ◽

Vol 49 (268) ◽

pp. 778-785 ◽

Cited By ~ 30

Author(s):

Herman Chernoff ◽

Gerald J. Lieberman

Keyword(s):

Probability Paper ◽

Normal Probability

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Effects of Notch Size on Strength Distribution of Ceramic Components

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.1548 ◽

2007 ◽

Vol 353-358 ◽

pp. 1548-1551

Author(s):

Feng Hui Wang ◽

Ying Xi Wu

Keyword(s):

Fracture Strength ◽

Strength Distribution ◽

Smooth Specimen ◽

Notch Radius ◽

Notched Specimen ◽

The Past ◽

Weakest Link ◽

Probability Paper ◽

Normal Probability ◽

Ceramic Components

The dependence of strength on notch radii of ceramic components is presented. The strength is exponential decay as the notch radius decrease, the smooth specimen that corresponds to the infinity notch radius topped the fracture strength, but the lowest value relys on the micro feature of the materials. Plotted the strengths on Weibull and Normal probability paper, the fitness coefficients reveal that the strength of smooth specimen, as the past literatures indicated, follows Weibull distribution, but the strength of notched specimen follows Normal distribution better. Such result is due to the fact that the decreasing notch radius reduces and limits the effective original fracture volume, when the notch becomes a slim crack, the weakest link place becomes deterministic.

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