Re: [PSES] RFID Reader Integration

[Charlie Blackham]

Brian

A radio transmitter that is certified for USA and Canada probably does not need 
any further certification (subject to Grant Notes and EMF) but does require 
testing - see FCC KDB 996369 
https://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm?id=44637=P

For Europe, a full "assessment" against the Radio Equipment Directive is 
required, which will almost certainly include some testing - further guidance 
in 
http://redca.eu/Unrestricted%20Documents/TGN/REDCA%20TGN%2001%20RED%20Radio%20equipment%20modules%20V1.2a%20March%202020.pdf

Best regards
Charlie

Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: https://sulisconsultants.com/
Registered in England and Wales, number 05466247

From: David Shidlovsky 
Sent: 23 February 2022 05:39
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] RFID Reader Integration

Hi
As someone who works in a test lab my recommendation is that if you are not 
manufacturing a radio device (designing and manufacturing the 
transmitter/receiver and the whole product), you should by a module that has 
both CE mark and FCC/ISED modular approval.
If the module has FCC/ISED modular approval, as long as you maintain the grant 
conditions no further radio testing is required for FCC/ISED. When in doubt, 
contact a TCB.
If you plan to sell your product in Europe, then if the module has CE, minimum 
testing should be performed on the whole device to make sure the electronics of 
your device do not affect the module. If all is ok, you can issue a DOC for 
Europe.

Best Regards,
David Shidlowsky
Technical Reviewer
[cid:image001.jpg@01D82949.F3D2A790]
Address 1 Bat-Sheva St. POB 6117, LOD7120101   Israel
Tel: 972-8-9186100 Ext. 213 Direct: 972-8-9186113   Fax: 972-8-9153101
Mail: dav...@itlglobal.org
Web www.itlglobal.org

[cid:image002.png@01D82949.F3D2A790]Waze ITL: https://waze.com/ul/hsv8vccn2j
[cid:image003.jpg@01D82949.F3D2A790]
 https://www.linkedin.com/company/itl-israel-testing-laboratories/
[cid:image004.jpg@01D82949.F3D2A790][cid:image005.jpg@01D82949.F3D2A790]
[cid:image006.jpg@01D82949.F3D2A790]




From: MIKE SHERMAN mailto:msherma...@comcast.net>>
Sent: Wednesday, February 23, 2022 2:21 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] RFID Reader Integration

Brian -
Be careful! Although very low powered, regulators still want to regulate!
We bought an RFID chip and created the antenna via a trace on the board. Guess 
what-that meant there was no modular approval=we got to do lots of testing!
Next time we'll choose differently.
Mike Sherman
On 02/22/2022 11:36 AM Brian Kunde 
mailto:bkundew...@gmail.com>> wrote:



I know nothing about the regulatory requirements of an RFID Reader but I assume 
it has a transceiver so it is considered an Intentional Radiator.

If I buy a reader over-the-counter in one country, can I use it in another 
country? Or, like WiFi and Bluetooth, do I have to have a Reader that is 
Certified for every country/market?

If I want to integrate an RFID reader into an electronic device or machine, can 
I buy pre-certified modules for a worldwide market?  Or will I have to have the 
entire electronic device certified?

What are my options?  Any insight would be helpful and appreciated.

Thanks,
The Other Brian


-


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mailto:emc-p...@ieee.org>>

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Website: 

Re: [PSES] Risk assessment versus HBSE

[Douglas E Powell]

Looks very interesting, I'll have to fit it into my reading list

Doug



On Wed, Feb 23, 2022 at 5:42 PM Richard Nute  wrote:

>
>
>
>
> Hi Doug:
>
>
>
> See:
>
>
>
>
> https://www.tandfonline.com/doi/pdf/10.1080/01446193.2016.1274418?needAccess=true
>
>
>
> Best regards,
>
> Rich
>
>
>
>
>
> *From:* Douglas Nix 
> *Sent:* Wednesday, February 23, 2022 8:57 AM
> *To:* Richard Nute 
> *Cc:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] Risk assessment versus HBSE
>
>
>
> Hi Rich,
>
>
>
> Your points are well taken.
>
>
>
> There are some good ISO standards that relate to exposure to hot and cold
> temperatures. These standards take the type of material, and therefore the
> transfer rate, of heat into account and are quite useful IMO.
>
>
>
> You are right about the HBSE model, and I think that we need both
> approaches, that is HBSE and “conventional” risk assessment. The issue is
> always this: what do you do when you don’t have any data? Practitioners
> must start with what they know, and that usually means starting with
> qualitative risk assessments. This is especially true in the broader OHS
> sector where these types of assessments are used for workplace inspections.
> The problem is that when we attach arbitrary numeric values to qualitative
> scales people start to believe that the math is somehow “right” regardless
> of how arbitrary in the input data. Even if the math is correct, GIGO. This
> is what plagues the application of conventional risk assessment techniques
> and why Cox, Quintino and others have been raising the alarm for so many
> years.
>
>
>
> We’re now in a place where the EU has a semi-quantitative (yes I hate that
> term too, but it’s descriptive) risk assessment tool built into the RAPEX
> directive for use on consumer products and white goods. This same tool has
> been adopted by the US CPSC, although they are not making this widely
> known. Health Canada has their own methodology for the same purpose, and
> I’m quite sure that if we were to examine the methods used by the national
> health and safety agencies in any country that has such an entity, we would
> find that they too have some method like the RAPEX/CPSC or Health Canada
> methods. So, for now we are stuck with what we have. At least we are
> getting manufacturers to think about risk, rather than “just” hazards.
>
>
>
> Progress comes slowly…
>
>
>
> --
>
> Doug Nix
>
> d...@mac.com
>
> (519) 729-5704
>
>
>
> "Opportunity is missed by most people because it is dressed in overalls
> and looks like work." - Thomas A. Edison
>
>
>
> On 22-Feb-22, at 19:03, Richard Nute  wrote:
>
>
>
>
>
>
>
> Hi Doug:
>
>
>
> Thanks for your comments.
>
>
>
> What bothers me about risk assessment is that the committees that have
> written the standards requiring risk assessment have not critically
> evaluated the risk assessment process.  If they had done so, we would not
> have the process as we know it today.
>
>
>
> Actually, I do not fully agree with the Gibson finding that energy causes
> injury.  I can show that the injury parameter is energy per unit time,
> e.g., joules/second.  The body can absorb energy slowly without injury, but
> not quickly.  Consider that a car with people in it can brake or stop
> without causing injury to the passengers, but cannot “crash” to a stop
> where injury is likely.  In both cases, the kinetic energy to stop is the
> same, but the kinetic energy per time to stop is low in braking, but high
> in crashing.
>
>
>
> The attached picture is that of catching three objects and assumes the
> deceleration time is the same for each object.  Note that when we catch an
> object, we can catch it “slowly” and distribute the energy over a longer
> time than catching it “directly.”  I submit this as proof that energy per
> unit time is the parameter that causes injury.
>
>
>
> HBSE does indeed have (or can have) energy criteria for each form of
> energy.  However, I agree that some energy data is not readily available
> and must be researched.  And, using the energy model can be quite complex.
> For example, injury from thermal energy is often simply taken as accessible
> temperature, sometimes including a time of contact.  Using a single
> parameter, temperature, or including time of contact parameter, does not
> address the difference between an aluminum block and aluminum foil (which
> is the issue some members of IEC TC108/HBSDT are addressing).   Or the
> difference between an aluminum block and a plastic block.
>
>
>
> Best regards,
>
> Rich
>
>
>
>
>
>
>
> *From:* Douglas Nix 
> *Sent:* Monday, February 14, 2022 12:46 PM
> *To:* Richard Nute 
> *Cc:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] Risk assessment versus HBSE
>
>
>
> Hi Rich,
>
>
>
> I have to admit that I’ve been thinking about your reply all weekend.
>
>
>
> As you know, I teach machinery risk assessment and consult in this area
> regularly. I want to stipulate that there are some significant issues with
> risk assessment the way 

Re: [PSES] Risk assessment versus HBSE

[Richard Nute]

 

 

Hi Doug:  

 

See:

 

https://www.tandfonline.com/doi/pdf/10.1080/01446193.2016.1274418?needAccess=true

 

Best regards,

Rich 

 

 

From: Douglas Nix  
Sent: Wednesday, February 23, 2022 8:57 AM
To: Richard Nute 
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Risk assessment versus HBSE

 

Hi Rich,

 

Your points are well taken.

 

There are some good ISO standards that relate to exposure to hot and cold 
temperatures. These standards take the type of material, and therefore the 
transfer rate, of heat into account and are quite useful IMO.

 

You are right about the HBSE model, and I think that we need both approaches, 
that is HBSE and “conventional” risk assessment. The issue is always this: what 
do you do when you don’t have any data? Practitioners must start with what they 
know, and that usually means starting with qualitative risk assessments. This 
is especially true in the broader OHS sector where these types of assessments 
are used for workplace inspections. The problem is that when we attach 
arbitrary numeric values to qualitative scales people start to believe that the 
math is somehow “right” regardless of how arbitrary in the input data. Even if 
the math is correct, GIGO. This is what plagues the application of conventional 
risk assessment techniques and why Cox, Quintino and others have been raising 
the alarm for so many years.

 

We’re now in a place where the EU has a semi-quantitative (yes I hate that term 
too, but it’s descriptive) risk assessment tool built into the RAPEX directive 
for use on consumer products and white goods. This same tool has been adopted 
by the US CPSC, although they are not making this widely known. Health Canada 
has their own methodology for the same purpose, and I’m quite sure that if we 
were to examine the methods used by the national health and safety agencies in 
any country that has such an entity, we would find that they too have some 
method like the RAPEX/CPSC or Health Canada methods. So, for now we are stuck 
with what we have. At least we are getting manufacturers to think about risk, 
rather than “just” hazards.

 

Progress comes slowly…

 

--

Doug Nix

d...@mac.com  

(519) 729-5704

 

"Opportunity is missed by most people because it is dressed in overalls and 
looks like work." - Thomas A. Edison





On 22-Feb-22, at 19:03, Richard Nute mailto:ri...@ieee.org> > 
wrote:

 

 

 

Hi Doug:

 

Thanks for your comments.

 

What bothers me about risk assessment is that the committees that have written 
the standards requiring risk assessment have not critically evaluated the risk 
assessment process.  If they had done so, we would not have the process as we 
know it today.  

 

Actually, I do not fully agree with the Gibson finding that energy causes 
injury.  I can show that the injury parameter is energy per unit time, e.g., 
joules/second.  The body can absorb energy slowly without injury, but not 
quickly.  Consider that a car with people in it can brake or stop without 
causing injury to the passengers, but cannot “crash” to a stop where injury is 
likely.  In both cases, the kinetic energy to stop is the same, but the kinetic 
energy per time to stop is low in braking, but high in crashing.  

 

The attached picture is that of catching three objects and assumes the 
deceleration time is the same for each object.  Note that when we catch an 
object, we can catch it “slowly” and distribute the energy over a longer time 
than catching it “directly.”  I submit this as proof that energy per unit time 
is the parameter that causes injury.

 

HBSE does indeed have (or can have) energy criteria for each form of energy.  
However, I agree that some energy data is not readily available and must be 
researched.  And, using the energy model can be quite complex.  For example, 
injury from thermal energy is often simply taken as accessible temperature, 
sometimes including a time of contact.  Using a single parameter, temperature, 
or including time of contact parameter, does not address the difference between 
an aluminum block and aluminum foil (which is the issue some members of IEC 
TC108/HBSDT are addressing).   Or the difference between an aluminum block and 
a plastic block. 

 

Best regards,

Rich

 

 

 

From: Douglas Nix mailto:d...@mac.com> > 
Sent: Monday, February 14, 2022 12:46 PM
To: Richard Nute mailto:ri...@ieee.org> >
Cc: EMC-PSTC@LISTSERV.IEEE.ORG  
Subject: Re: [PSES] Risk assessment versus HBSE

 

Hi Rich,

 

I have to admit that I’ve been thinking about your reply all weekend.

 

As you know, I teach machinery risk assessment and consult in this area 
regularly. I want to stipulate that there are some significant issues with risk 
assessment the way it is most commonly applied in industry, see my list of 
references on this topic at the end of my message. 

 

The inherent subjectivity of risk assessments that are performed without 

Re: [PSES] Risk assessment versus HBSE

[Douglas E Powell]

Mark,

I did something along those lines back in 2012 when a question came up
about the need for a finger guard on a low power fan. In order to better
understand the possibility of injury, I estimated the surface contact area
of the blade edge against a finger, rotational speed and mass of the fan
impeller in terms of mechanical energy. I think I converted to J/mm^2. In
any case, the result was quite low and in my opinion "safe". To prove it
out, I was willing to first try jamming  a #2 pencil, and then my finger
into the fan while running at full speed. So far, 10 years later, I still
have my fully intact finger, but sadly the pencil was eventually used or
otherwise lost.

-Doug

Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -07:00) Mountain Time (US-MST)


On Wed, Feb 23, 2022 at 4:04 PM Mark Ortlieb 
wrote:

> Hello all,
>
> I am keenly interested in this discussion on energy vs energy/time with
> respect to causing injury, especially from a physical contact perspective.
> A couple of other considerations that are worthy to be included in such a
> discussion, which would add another layer of complexity would be:
>
>- The geometry of the object that comes into contact with the body.
>Take a needle as an example, or a knife edge. Let's say the needle is very
>light (a gram or two) and moving very slowly (1 mm/hour), at some point
>severe injury could take place through piercing of skin. Real world
>scenario aside, this illustrates a different kind of potential harm that
>can be inflicted. I don't know if there is a practical way to incorporate
>such a factor into an equation (such as the Energy Transfer equation), but
>certainly it needs to be included as part of a thorough analysis.
>- The kind of "victim" person being considered, for example a child vs
>an adult. A child may not be able to withstand the same level of energy
>transfer as an adult, or may be subject to a different kind of injury as
>the result of an energy transfer, that is, a secondary injury, such as
>being more easily pushed down and hitting their head on the floor. In fact,
>I am interested to know if there are others out there who are aware of any
>data or studies regarding impact with children.
>
> Thanks,
>
> Mark
>
>
>
>
>
>
> Hi Doug:
>
>
>
> Thanks for your comments.
>
>
>
> What bothers me about risk assessment is that the committees that have
> written the standards requiring risk assessment have not critically
> evaluated the risk assessment process.  If they had done so, we would not
> have the process as we know it today.
>
>
>
> Actually, I do not fully agree with the Gibson finding that energy causes
> injury.  I can show that the injury parameter is energy per unit time,
> e.g., joules/second.  The body can absorb energy slowly without injury, but
> not quickly.  Consider that a car with people in it can brake or stop
> without causing injury to the passengers, but cannot “crash” to a stop
> where injury is likely.  In both cases, the kinetic energy to stop is the
> same, but the kinetic energy per time to stop is low in braking, but high
> in crashing.
>
>
>
> The attached picture is that of catching three objects and assumes the
> deceleration time is the same for each object.  Note that when we catch an
> object, we can catch it “slowly” and distribute the energy over a longer
> time than catching it “directly.”  I submit this as proof that energy per
> unit time is the parameter that causes injury.
>
>
>
> HBSE does indeed have (or can have) energy criteria for each form of
> energy.  However, I agree that some energy data is not readily available
> and must be researched.  And, using the energy model can be quite complex.
> For example, injury from thermal energy is often simply taken as accessible
> temperature, sometimes including a time of contact.  Using a single
> parameter, temperature, or including time of contact parameter, does not
> address the difference between an aluminum block and aluminum foil (which
> is the issue some members of IEC TC108/HBSDT are addressing).   Or the
> difference between an aluminum block and a plastic block.
>
>
>
> Best regards,
>
> Rich
>
>
>
>
>
>
>
> *From:* Douglas Nix  
> *Sent:* Monday, February 14, 2022 12:46 PM
> *To:* Richard Nute  
> *Cc:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] Risk assessment versus HBSE
>
>
>
> Hi Rich,
>
>
>
> I have to admit that I’ve been thinking about your reply all weekend.
>
>
>
> As you know, I teach machinery risk assessment and consult in this area
> regularly. I want to stipulate that there are some significant issues with
> risk assessment the way it is most commonly applied in industry, see my
> list of references on this topic at the end of my message.
>
>
>
> The inherent subjectivity of risk assessments that are performed without
> empirical data is unquestioned. The difficulty is 

Re: [PSES] Risk assessment versus HBSE

[Mark Ortlieb]

Hello all,

I am keenly interested in this discussion on energy vs energy/time with 
respect to causing injury, especially from a physical contact 
perspective. A couple of other considerations that are worthy to be 
included in such a discussion, which would add another layer of 
complexity would be:


 * The geometry of the object that comes into contact with the body.
   Take a needle as an example, or a knife edge. Let's say the needle
   is very light (a gram or two) and moving very slowly (1 mm/hour), at
   some point severe injury could take place through piercing of skin.
   Real world scenario aside, this illustrates a different kind of
   potential harm that can be inflicted. I don't know if there is a
   practical way to incorporate such a factor into an equation (such as
   the Energy Transfer equation), but certainly it needs to be included
   as part of a thorough analysis.
 * The kind of "victim" person being considered, for example a child vs
   an adult. A child may not be able to withstand the same level of
   energy transfer as an adult, or may be subject to a different kind
   of injury as the result of an energy transfer, that is, a secondary
   injury, such as being more easily pushed down and hitting their head
   on the floor. In fact, I am interested to know if there are others
   out there who are aware of any data or studies regarding impact with
   children.

Thanks,

Mark



Hi Doug:

Thanks for your comments.

What bothers me about risk assessment is that the committees that have 
written the standards requiring risk assessment have not critically 
evaluated the risk assessment process.  If they had done so, we would 
not have the process as we know it today.


Actually, I do not fully agree with the Gibson finding that energy 
causes injury.  I can show that the injury parameter is energy per 
unit time, e.g., joules/second.  The body can absorb energy slowly 
without injury, but not quickly.  Consider that a car with people in 
it can brake or stop without causing injury to the passengers, but 
cannot “crash” to a stop where injury is likely.  In both cases, the 
kinetic energy to stop is the same, but the kinetic energy per time to 
stop is low in braking, but high in crashing.


The attached picture is that of catching three objects and assumes the 
deceleration time is the same for each object.  Note that when we 
catch an object, we can catch it “slowly” and distribute the energy 
over a longer time than catching it “directly.”  I submit this as 
proof that energy per unit time is the parameter that causes injury.


HBSE does indeed have (or can have) energy criteria for each form of 
energy.  However, I agree that some energy data is not readily 
available and must be researched.  And, using the energy model can be 
quite complex.  For example, injury from thermal energy is often 
simply taken as accessible temperature, sometimes including a time of 
contact.  Using a single parameter, temperature, or including time of 
contact parameter, does not address the difference between an aluminum 
block and aluminum foil (which is the issue some members of IEC 
TC108/HBSDT are addressing).   Or the difference between an aluminum 
block and a plastic block.


Best regards,

Rich

*From:* Douglas Nix 
*Sent:* Monday, February 14, 2022 12:46 PM
*To:* Richard Nute 
*Cc:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Risk assessment versus HBSE

Hi Rich,

I have to admit that I’ve been thinking about your reply all weekend.

As you know, I teach machinery risk assessment and consult in this 
area regularly. I want to stipulate that there are some significant 
issues with risk assessment the way it is most commonly applied in 
industry, see my list of references on this topic at the end of my 
message.


The inherent subjectivity of risk assessments that are performed 
without empirical data is unquestioned. The difficulty is that for 
many areas of human endeavour we have no empirical data, and try as we 
might we cannot calculate without numeric data. Nevertheless, we must 
be able to make risk-based decisions when designing products and 
equipment, and so we muddle along with the best tools that we have, 
hopefully while recognizing their flaws.


The HBSE model is a good one, and it fits machinery applications as 
readily as does risk assessment, however, the risk assessment methods 
that are used today have a history that stretches back to the 1960s, 
while the HBSE model is much younger. This doesn’t take away from HBSE 
in any way for me, but it does have an impact on the broader 
acceptance of the method since it is not yet as widely known as 
“conventional” risk assessment. None of the the standards in the 
machinery safety sector recognize the method as yet, so getting 
regulators and users to consider the method is a challenge.


HBSE also suffers from issues with lack of data when it comes to 
characterizing some hazards, leaving the user to estimate the 

Re: [PSES] Risk assessment versus HBSE

[Douglas Nix]

Hi Rich,

Your points are well taken.

There are some good ISO standards that relate to exposure to hot and cold 
temperatures. These standards take the type of material, and therefore the 
transfer rate, of heat into account and are quite useful IMO.

You are right about the HBSE model, and I think that we need both approaches, 
that is HBSE and “conventional” risk assessment. The issue is always this: what 
do you do when you don’t have any data? Practitioners must start with what they 
know, and that usually means starting with qualitative risk assessments. This 
is especially true in the broader OHS sector where these types of assessments 
are used for workplace inspections. The problem is that when we attach 
arbitrary numeric values to qualitative scales people start to believe that the 
math is somehow “right” regardless of how arbitrary in the input data. Even if 
the math is correct, GIGO. This is what plagues the application of conventional 
risk assessment techniques and why Cox, Quintino and others have been raising 
the alarm for so many years.

We’re now in a place where the EU has a semi-quantitative (yes I hate that term 
too, but it’s descriptive) risk assessment tool built into the RAPEX directive 
for use on consumer products and white goods. This same tool has been adopted 
by the US CPSC, although they are not making this widely known. Health Canada 
has their own methodology for the same purpose, and I’m quite sure that if we 
were to examine the methods used by the national health and safety agencies in 
any country that has such an entity, we would find that they too have some 
method like the RAPEX/CPSC or Health Canada methods. So, for now we are stuck 
with what we have. At least we are getting manufacturers to think about risk, 
rather than “just” hazards.

Progress comes slowly…

--
Doug Nix
d...@mac.com
(519) 729-5704

"Opportunity is missed by most people because it is dressed in overalls and 
looks like work." - Thomas A. Edison

> On 22-Feb-22, at 19:03, Richard Nute  wrote:
> 
> 
> 
> Hi Doug:
> 
> Thanks for your comments.
> 
> What bothers me about risk assessment is that the committees that have 
> written the standards requiring risk assessment have not critically evaluated 
> the risk assessment process.  If they had done so, we would not have the 
> process as we know it today.
> 
> Actually, I do not fully agree with the Gibson finding that energy causes 
> injury.  I can show that the injury parameter is energy per unit time, e.g., 
> joules/second.  The body can absorb energy slowly without injury, but not 
> quickly.  Consider that a car with people in it can brake or stop without 
> causing injury to the passengers, but cannot “crash” to a stop where injury 
> is likely.  In both cases, the kinetic energy to stop is the same, but the 
> kinetic energy per time to stop is low in braking, but high in crashing.
> 
> The attached picture is that of catching three objects and assumes the 
> deceleration time is the same for each object.  Note that when we catch an 
> object, we can catch it “slowly” and distribute the energy over a longer time 
> than catching it “directly.”  I submit this as proof that energy per unit 
> time is the parameter that causes injury.
> 
> HBSE does indeed have (or can have) energy criteria for each form of energy.  
> However, I agree that some energy data is not readily available and must be 
> researched.  And, using the energy model can be quite complex.  For example, 
> injury from thermal energy is often simply taken as accessible temperature, 
> sometimes including a time of contact.  Using a single parameter, 
> temperature, or including time of contact parameter, does not address the 
> difference between an aluminum block and aluminum foil (which is the issue 
> some members of IEC TC108/HBSDT are addressing).   Or the difference between 
> an aluminum block and a plastic block.
> 
> Best regards,
> Rich
> 
> 
> 
> From: Douglas Nix 
> Sent: Monday, February 14, 2022 12:46 PM
> To: Richard Nute 
> Cc: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: Re: [PSES] Risk assessment versus HBSE
> 
> Hi Rich,
> 
> I have to admit that I’ve been thinking about your reply all weekend.
> 
> As you know, I teach machinery risk assessment and consult in this area 
> regularly. I want to stipulate that there are some significant issues with 
> risk assessment the way it is most commonly applied in industry, see my list 
> of references on this topic at the end of my message.
> 
> The inherent subjectivity of risk assessments that are performed without 
> empirical data is unquestioned. The difficulty is that for many areas of 
> human endeavour we have no empirical data, and try as we might we cannot 
> calculate without numeric data. Nevertheless, we must be able to make 
> risk-based decisions when designing products and equipment, and so we muddle 
> along with the best tools that we have, hopefully while recognizing their 
> flaws.
> 
> The HBSE