Characteristics of distribution – estimates of center and spread for Parametric Distribution Analysis (Right Censoring)

The Characteristics of Distribution table displays measures of the center and spread of the distribution.

The mean time to failure (MTTF) and the median estimates are measures of the center of the distribution, whereas the standard deviation and the interquartile range (IQR) are measures of the spread of the distribution.

Use these values only when the distribution fits the data adequately. If the distribution fits the data poorly, these estimates will be inaccurate. Use the distribution ID plot, probability plot, and goodness-of-fit measures to determine whether the distribution adequately fits the data.

Example output

Characteristics of Distribution Standard 95.0% Normal CI Estimate Error Lower Upper Mean(MTTF) 67.4153 5.55245 57.3656 79.2255 Standard Deviation 34.8145 6.79827 23.7435 51.0476 Median 59.8995 4.31085 52.0192 68.9735 First Quartile(Q1) 43.1516 3.29526 37.1531 50.1186 Third Quartile(Q3) 83.1475 7.37690 69.8763 98.9392 Interquartile Range(IQR) 39.9959 6.33317 29.3245 54.5505


The MTTF (67.4153) and the standard deviation (34.8145) are sensitive statistics because the tails in a skewed distribution and outliers significantly affect the values.

The median (59.8995) and the IQR (39.9959) are resistant statistics because the tails in a skewed distribution and outliers do not significantly affect the values.

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