IH Statistics and Decision Making

IH Statistics and Decision Making I and II

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.


Paul Hewett Ph.D. CIH

Course Description

These web PDCs introduce the participant to Industrial hygiene (IH) statistics, which are those statistical methods and concepts that have proved useful for characterizing occupational exposure data and for IH decision making. (See the list of Prerequisites.)

Part I covers the statistical methods used to estimate the parameters of the exposure profile (i.e., distribution of exposures). Included is an introduction to the normal, z-value, and lognormal distributions; distribution parameters vs. sample statistics; goodness-of-fit testing; descriptive statistics; compliance statistics (percentiles and exceedance fractions); confidence intervals and hypothesis testing; and non-parametric statistics.

Part II focuses on comparison tests (parametric and non-parametric), trend analysis and control charts, as well as the application of ANOVA (analysis-of-variance) and the related COV (components-of-variance). Included is a presentation on Data Quality issues, as well as introductions to Censored Data Analysis and Bayesian Decision Analysis.

Each 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.

To assist the student, EAS Inc. will provide a student version of the new IHDataAnalyst-2020 (IHDA) program.

Learning Objectives

Part I

  • Ability to calculate and interpret both descriptive and compliance statistics.
  • Ability to calculate and interpret confidence intervals for the most commonly used compliance statistics.
  • Ability to use both subjective and objective goodness-of-fit procedures to validate the use of the lognormal distribution model.
  • Appreciation of the relationships between exposure profiles (i.e., distributions), exposure data, sample statistics, and IH decision making.
  • Awareness of the difference between statistics-based decision making and rule-based decision making.
  • Awareness of the major issues, pitfalls, and problems associated with the analysis and interpretation of occupational exposure data.

Part II

  • Ability to compare a dataset to different Decision Statistics (i.e., limits; environmental vs. occupational).
  • Ability to compare two exposure datasets – e.g., before and after engineering controls – using parametric and non-parametric methods.
  • Ability to use ANOVA (analysis-of-variance) methods to evaluate the construction of a Similar Exposure Group (SEG).
  • Ability to use COV (components-of-variance) to estimate the fraction of workers having individual 95th percentiles exceeding an occupational limit, or the fraction of workers having individual mean exposures exceeding an environmental limits.
  • Ability to evaluate trends in occupational exposure data.
  • Familiarity with Data Quality issues.


  • 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), or the AIHA IHStats spreadsheet.
  • Recommended reading prior to the WebPDC:
    • Hewett, P. (2007): Technical Report 07-02 – Industrial Hygiene Exposure Assessment – Data Collection and Management. Exposure Assessment Solutions, Inc.
    • Hewett, P. (2007): Technical Report 07-03 – Industrial Hygiene Exposure Assessment – Data Analysis and Interpretation. Exposure Assessment Solutions, Inc

Presentation List – Part I

  • AIHA Exposure Control Model
  • Baseline Survey Simulator Workshop
  • Introduction to the IH Data Analyst – Student version
  • Distributions
  • Descriptive and Compliance Statistics
  • Goodness-of-fit
  • Order Statistics
  • Decision making using statistics
  • Exposure Assessment Issues and Pitfalls

Presentation List – Part II

  • Comparison Tests – Parametric and Non-Parametric
  • Analysis-of-Variance  and Components-of-Variance
  • Control Charts and Trend Analysis
  • Data Quality Issues
  • Introduction to Censored Data Analysis and Bayesian Decision Analysis


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. Registration is per participant, not per viewing site. Each participant must register.  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 at least the day before 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.