SAS Note V6-RELIABILITY-H020

From: SAS Technical Support (tsdlist@unx.sas.com)
Date: Tue Oct 22 2002 - 07:01:43 EDT

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    V6-RELIABILITY-H020 ***Alert Note***

    Incorrect output is produced when using the THRESHOLD option

    Product: QC
    Component: RELIABILITY
    Priority: ALERT

      PROC RELIABILITY allows a fixed threshold, g, to be specified for the
      Weibull, lognormal and loglogistic distributions. The procedure
      computes estimates for the distribution parameters using Y = T - g as
      the response data, instead of the original lifetimes T. The
      distribution percentiles and confidence limits reported from the
      PROBPLOT, ANALYZE and RELATIONPLOT statements, as well as the quantiles
      produced with the OBSTATS option on the MODEL statement are incorrect.
      The correct value for each of these statistics is the reported value
      plus the fixed threshold g.

      In addition, survival function estimates created with the SURVTIME=
      option on the PROBPLOT, ANALYZE and RELATIONPLOT statements assume a
      survival time on the scale of Y, instead of T, and will lead to
      incorrect results if requested survival times are specified in terms of
      the original data, T. Survival function estimates created with the
      OBSTATS(SURVIVAL) option on the MODEL statement do not account for the
      threshold parameter and are also incorrect.

    Keywords:
      incorrect output threshold survtime obstats survival incorrstat
      incorrout
      H020

    SAS Note Revised On: Mon, 21 Oct 2002

    System Release Reported Release Fixed

    AIX/6000 6.12 TS020
    HP-UX Operating Systems 6.12 TS020
    IBM OS/2 6.12 TS020
    Solaris 6.12 TS020
    OpenVMS Alpha 6.12 TS020
    Windows 3.11 6.12 TS020
    Windows NT 6.12 TS020
    Windows 95 6.12 TS020
    Compaq Tru64 Unix 6.12 TS040
    Macintosh 6.12 TS040

    No Fixes Available

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