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 Error	95.0% Normal CI
	Estimate	Standard 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

Interpretation

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.