Project Name 1 Industrial Hygiene Monitoring Introduction To Bayesian Statistics Dave Pearson, Djon Gentry, Tim Allers

Project Name 2 INTRODUCTIONTO BAYESIAN STATISTICS

Project Name 3 Introduction to Bayesian Statistics What is Bayesian Statistics? –An approach to statistics in which estimates are based on a synthesis of a prior distribution and current sample data. –Belief that something will happen is based on past observation.

Project Name 4 Introduction to Bayesian Statistics What is Bayesian Statistics? – Everyday Example –When you cross a road, you may need to do a full "analysis" of the data concerning oncoming traffic (How fast? How big is the gap? Does the driver look like a maniac? Have they seen me?) but one thing you don't consider: once the car has gone past and I step out on the road; what is the chance that it will back-up and run me over –In essence we've performed a Bayesian calculation based on a lifetime of crossing the road. We have a strong belief, based on experience, that the car will not back up.

Project Name 5 Introduction to Bayesian Statistics Why use Bayesian Statistics? –Quantifiable validation of prior and future PPE & engineering control decisions –To predict future exposures and establish PPE and engineering control requirements –Typical employee works 220 days/year. 4 samples represents roughly 2% of their annual exposure profile –Statistically valid decision making with as few as 3 samples –New EHS Standard requires that a statistical tool be used –Provides a consistent process for IH decision making –Risk Management Decision making based on defensible data

Project Name 6 From: Paul Hewett, Ph.D., CIH & John Mulhaussen, Ph.D., CIH

Project Name 7 From: Paul Hewett, Ph.D., CIH & John Mulhaussen, Ph.D., CIH

Project Name 8 From: Paul Hewett, Ph.D., CIH & John Mulhaussen, Ph.D., CIH

Project Name 9 From: Paul Hewett, Ph.D., CIH & John Mulhaussen, Ph.D., CIH

Project Name 10 From: Paul Hewett, Ph.D., CIH & John Mulhaussen, Ph.D., CIH

Project Name 11 From: Paul Hewett, Ph.D., CIH & John Mulhaussen, Ph.D., CIH

Project Name 12 Trivial Professional Judgment * Highly-Controlled Well-Controlled Controlled Poorly-Controlled * Qualitative Exposure Assessment Input 2 Bayesian Decision Analysis

Project Name 13 Opening & Running the IHDataAnalyst Software

Project Name 14 Starting the IHDataAnalyst Program On your desktop click the IHDataAnalyst icon. Either this Or This

Project Name 15 The Program will Launch

Project Name 16 Input Facility Information Here The facility information should reflect the area where the Industrial Hygiene monitoring data was obtained.

Project Name 17 Input the Substance Information Here. This section would include the chemical name or if the monitoring was for noise, the word “noise” Next, click the drop-down box and select the unit of measure.

Project Name 18 Input IH Data Here Input the monitoring data for the Substance monitored in the “Conc” column. Place a “Y” in the “LOD” column if the data is a less than (<) value.

Project Name 19 Crunching the Numbers Click the “Calculate All” button on the toolbar.

Project Name 20 IH Data Input & Decision Making

Project Name 21 There’ s a lot of Stats in there! Help me sift through it. XO.95 = 95% of your data should fall below this point. 95%UCL = 95% confident that any new data will fall below this number based on existing data. BDA Charts – Indication of how well controlled your process is. PPE Charts – J&J IH has agreed to use “75% or >” for deciding if PPE is warranted and the appropriate APF.

Project Name 22 Example 1 Ethinyl Estradiol All samples less than half the OEL

Project Name 23 Example 1 All 5 samples < XO.95 95% UCL

Project Name 24 Example 1

Project Name 25 < 75% What Is Your Decision?

Project Name 26 Removed “<“ Decision Probability Increased

Project Name 27 Added one more data point. Now > 75%. Feeling more comfortable with Making decision for no respirators DON’T FORGET TO CALCULATE ALL!!!

Project Name 28 By doubling the original data Resulted in

Project Name 29 Doubled the data. Greater comfort in PPE decision Now 84.5%

Project Name 30 Report Format What does this program provide as far as from a written document?

Project Name 31 Report - Example 1

Project Name 32 Report - Example 1

Project Name 33 Report – Example 1

Project Name 34 Report – Example 1

Project Name 35 Example 2 Cobalt dust/fume Sample results at or less than OEL Look at your data. What is it trying to tell you? Knowing when to take additional samples and knowing when to stop sampling and implement controls.

Project Name 36 8 data points ranging From 1/10 to 1 X OEL

Project Name 37 BDA Charts = 4 Poorly Controlled

Project Name 38 PPE Charts = 10X

Project Name 39 Decision Making BDA Charts indicate Poorly Controlled PPE Charts indicate the need for 10X APF What are your next steps? Make sure employees performing this work are included in the RPP, Med Surveillance, and provide a minimum of 10x protection respirators. Do you think that obtaining additional samples will help at this point? Probably Not at this time Enhance engineering controls, then re-sample After engineering controls have been implemented, new data collected should be separated from the previous data collected during Poor Controls

Project Name 40 Example 3 8 Hr TWA vs. Task Duration You obtain samples during a specific task The task lasts approximately 30 minutes for the day Confirmed no other exposure to this or similar compounds the remainder of the day Compound being measured does not have acute hazards associated with it and there is no assigned STEL. What decisions are you making based on the sampling results?

Project Name 41 Example 3 – 8 Hr vs. Task All results are from sampling 30 minute task Results are 1 to 3 X OEL (No STEL)

Project Name 42 Example 3 – 8 Hr vs. Task PPE Charts indicate the need For employing 10X APF

Project Name 43 Example 3 – 8 Hr vs. Task However, if one were to convert results from lab into 8 HR TWA, assigning ZERO remainder of the day

Project Name 44 Example 3 – 8 Hr vs. Task The PPE Chart now indicates No Respiratory Protection needed

Project Name 45 What Decisions Are You Making? Are you “In Compliance”? Is compliance the only thing we should be looking at here? What are you doing in the absence of an STEL? Are you confident that the compound has no acute effects? Does your compound have an R-Sen D-Sen notation on the MSDS?

Project Name 46 Can We Make A Decision With Just 3 Samples?

Project Name 47 Can We Make A Decision With Just 3 Samples? 44% Confident with 10X 85% Confident with 25X 97% Confident with 50X

Project Name 48 QUESTIONS?