Censored Data Analysis

Location – (Web PDC)

Instructions regarding how to log onto the web PDC and the conference call phone number, as well as handouts, will emailed to the registered participants the week before the PDC.


Dr. Paul Hewett Ph.D.

Course Description

This web PDC introduce the participant to Censored Data Analysis (CDA). CDA refers to the analysis and interpretation of censored datasets.  (A censored dataset contains one or more non-detects.  (A non-detect refers to a sample where the true concentration was less than the laboratory reporting limit.)  (See the list of Prerequisites.)

The most common CDA methods will be introduced and used to estimate the parameters of the true worker or SEG exposure profile. These methods can be divided into families: substitution methods, log-probit regression methods, maximum likelihood estimation methods, and non-parametric methods. An estimate of the exposure profile 95th percentile (or mean) is then either calculated directly or calculated using the parameter estimates for the exposure profile. The several CDA methods differ in terms of bias, precision, overall accuracy, and ease of calculation. Recommendations will be presented for analyzing various types of censored datasets.

The PDC will last 3.0 hours, with an additional 30 minutes for Q&A.  Each participant will receive a certificate confirming participation in the PDC.

Learning Objectives

  • Recognition of the major issues and problems associated with the statistical analysis of censored datasets.
  • Familiarity with the four families of Censored Data Analysis (CDA) methods, and most commonly used method within each family.
  • Practice analyzing and interpreting censored datasets using the IHDataAnalyst-Student software.
  • Awareness of the bias and overall accuracy of the methods presented.
  • Recognition of the consequences of failing to properly analyze a censored dataset.


  • Participation in the webinar PDC “IH Statistics and Decision Making”, or a strong background in IH statistics.
  • Familiarity with the AIHA Exposure Assessment and Management Model (see the AIHA monograph “A Strategy for Assessing and Managing Occupational Exposures”, 4rd Edition (2015)
  • Working knowledge of the IHDataAnalyst (Professional or Student version).
  • Recommended reading prior to the WebPDC:
    • Hewett, P. and Ganser, G.H. (2007): A Comparison of Several Methods for Analyzing Censored Data. Annals of Occupational Hygiene 51:611-632.
    • “Appendix VIII – Analysis of Censored Data” in the AIHA monograph “in the AIHA monograph “A Strategy for Assessing and Managing Occupational Exposures”, 4rd Edition (2015).

Presentation List

  • Definitions, Assumptions, and Goals
  • Detects and Non-detects
  • Characteristics of Censored Datasets
  • Introduction to Parametric CDA Methods + Workshop
  • Introduction to Non-parametric CDA Methods + Workshop
  • Recommendations
  • Stump the Instructor – Analysis of Student Datasets
  • Q&A


See Registration page.

Cancellation Policy

See Registration page.

Read these notes before you sign up:

NOTE: The registration and participation policy for each Web PDC is the same as for a fixed location or on-site PDC. Each participant must register. Registration is per participant, not per viewing site. Only those registered should view and participant in this web PDC.

NOTE: The email address submitted at the time of payment will be used for all email communications and for logging onto the web PDC.

NOTE: This web PDC will presented using GoToMeeting. GoToMeeting must be installed on your computer. To install (usually takes less than two minutes), click on the GoToMeeting link above, scroll to the bottom of the page, and click on the link “Download GoToMeeting (for customers)”. If you do not have administrative privileges for your computer have your IT person install the GoToMeeting software well in advance of the web PDC.

NOTE: The conference call number will not be toll free. You will be responsible for any long distance phone charges if you do not have an unlimited long distance account. However, you may also connect using your computer speakers and microphone or headset (VoIP).

NOTE: See the “Prerequisites” below for software and freeware that will be helpful when taking this web PDC. To download and install the program(s) you must first be a registered member of www.easinc.co.