Do digital thermometers really work?

[jmccarty]

I have 2 digital oral thermometers, both from a major pharmacy that read about 2C different constantly and a mercury old style one that is somewhere in-between.  Not sure which if any of the 3 are accurate which makes me wonder how accurate any of these entryway checks are! 

[CaptainCarrot]

When I went to Jomtien Immigration to extend my visa I was barred from entering the building, and told to go back out and wait five minutes (she rightly guessed I had been out in the sun). I put it to her that I should actually wait INSIDE the building, specifically under the aircon just inside the door where I was standing. By the time we had finished discussing it I was back in an acceptable range ????

[thesetat2013]

22 hours ago, sezze said:

Can your body temp fall in such short time , no it can't . If there's like 30mins timeframe , then it can you are talking shorter .

Then how is it possible :

1: the temp meters are not the most accurate around , and are not calibrated , hence a difference between 2 different thermometers .

2: the measurement is surface measurement , which can be greatly influenced by external factors . Like the 1 you said going inside the building , maybe you walked in the sun for 2 minutes before , and so your skin temperature is higher . Next you go in AC room , and maybe even near the fridges , and take measurement again and highly likely your skin temp will have fallen by "massive" amount .

Correct temp measurement is inside body , to get your core temperature . Hence the old system of mouth / ass ( hopefully not the same thermometer haha ) and by lesser amount armpit . The IR thermometers can be accurate , but mostly they are used as fast detection method . As fast detection , they do not work 100% , but they give a indication of a possible fever .

Haha yes. Theses methods of taking temperature is really ridiculous. I got off my motorcycle and took off my helmet. I was sweating on my forehead. They took my temp and it was 38.4. I of course panicked but the hotel staff diligently tried again. 

I wiped my head off and waited a minute before they tried again. Ahh, this time 37.6. So the staff had me move to the side for another guest to be checked. When she returned to me, it was 30.2.. She then pointed to the aircon that I was standing in front of. Hence the lower reading. Finally she gave up and allowed me entrance to the elevator to go to my room. 

These measuring devices are totally inaccurate unless on controlled conditions. 

[Lacessit]

1 hour ago, Dazinoz said:

I don't know the temperature measuring range for the ones they are using. I have one that measures from -18C to 360C. It's for industrial usage. Its most accurate reading is mid range so trying to measure small body temperature changes is not very accurate.

 

I assume the ones they are using at check points have a much narrower measuring range but but most people know what assume does!!

Perhaps my post was lacking in clarity. What I meant was to be at least reproducible, operators should be trained to hold the instrument at a standard distance from the forehead, e.g. 6 inches. If they really want to do it properly, a forward probe that would touch the forehead to ensure a standard distance is achieved.

Repeatability, reproducibility, precision are all expressions of the same concept. Think of it as a grouping of bullet holes in a target, the closer they are, the better the repeatabilty. Reliability or accuracy expresses how close the result is to the true value, or whether the bullet holes are all in the bullseye.

Permit me to doubt the average mall employee has any grasp of those principles.

[Dazinoz]

20 minutes ago, Lacessit said:

Perhaps my post was lacking in clarity. What I meant was to be at least reproducible, operators should be trained to hold the instrument at a standard distance from the forehead, e.g. 6 inches. If they really want to do it properly, a forward probe that would touch the forehead to ensure a standard distance is achieved.

Repeatability, reproducibility, precision are all expressions of the same concept. Think of it as a grouping of bullet holes in a target, the closer they are, the better the repeatabilty. Reliability or accuracy expresses how close the result is to the true value, or whether the bullet holes are all in the bullseye.

Permit me to doubt the average mall employee has any grasp of those principles.

I know all about standardisation as I worked in an oil refinery that went through the standardisation process.

 

I found nothing wrong with your post but I thought the best to "attach" my post to. And you are also correct with the last post, Agree 100%.

[Almer]

On 4/15/2020 at 5:48 PM, Skallywag said:

No, many of the digital thermometers are not accurate here

Many of the digital thermometers are not calibrated originally, or re-calibrated often enough.   Ones that work should show at 36.2-36.6.  I had 33.2 at Terminal 21 a few weeks ago when they were still open.

 

Are you achy, tired, have chills, have a headache, swollen lymph glands?

If so, you may have a fever.

BigC just got out car 34,9 yikes, 5 minutes later i asked her to do it again before I went outside 36.1, they are measuring core temp which is normally 0.7 to 1 degree lower, if you want you true body temp its rubber glove time????

Edited April 16, 2020 by Almer
Error in figure

[sandyf]

On 4/15/2020 at 7:11 PM, sezze said:

Can your body temp fall in such short time , no it can't . If there's like 30mins timeframe , then it can you are talking shorter .

Then how is it possible :

1: the temp meters are not the most accurate around , and are not calibrated , hence a difference between 2 different thermometers .

2: the measurement is surface measurement , which can be greatly influenced by external factors . Like the 1 you said going inside the building , maybe you walked in the sun for 2 minutes before , and so your skin temperature is higher . Next you go in AC room , and maybe even near the fridges , and take measurement again and highly likely your skin temp will have fallen by "massive" amount .

Correct temp measurement is inside body , to get your core temperature . Hence the old system of mouth / ass ( hopefully not the same thermometer haha ) and by lesser amount armpit . The IR thermometers can be accurate , but mostly they are used as fast detection method . As fast detection , they do not work 100% , but they give a indication of a possible fever .

Quite. In a previous life I used manufacture thermal appliances, ovens and furnaces, and surface temperature measurement is an extremely complex subject.

There are so many variables it can never be anything other than a quick indication.

[warvet1970]

Another symptom of total ineptness of the junta ..

 

.. which should be indicative of why there's been such misguided action and chaos with immigration proposals-announcements-changes-indecisions-procedures ..

 

They can’t even do a temperature reading correctly ..

 

I went at the beginning of month to local immigration.  She placed the therma pistol near my head and then read it, showed it to her compatriot, chuckled, did it again, repeat, shook the gun as if it was broke and did it a third time.  She gave up.

 

In the past week going to the supermarket 2 visits same day separated by about 2 hours in afternoon, my reading was 34.4C.  This indicates such a low temp that I should be suffering from hypothermia.  Again, pistol point was near head, maybe several inches AWAY.

 

None of this made sense.  Well, of course.  My 'temp' was the ambient outdoor air temp. @ that very location, in the shade.  Further, I had just walked about a mile in heat greater than this, full sun, with no hat, both visits.  This thermography digital should be reading the temp of my SKIN.  You need to place the head of the pointed end on your forehead.

 

And one wonders why they are so backward with immigration.  Dah!

 

'A forehead (temporal) scanner is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.

 

' With a gentle stroke of the forehead it captures the naturally emitted heat from the skin over the temporal artery, taking 1,000 readings per second, selecting the most accurate. '

 

No one should have any concern about what is to be involving stays, visas, overstays et al. when Larry, Moe, & Curly Joe are in charge.  Just sit back and relax and enjoy the show.

[VocalNeal]

16 hours ago, Lacessit said:

Perhaps my post was lacking in clarity. What I meant was to be at least reproducible, operators should be trained to hold the instrument at a standard distance from the forehead, e.g. 6 inches. If they really want to do it properly, a forward probe that would touch the forehead to ensure a standard distance is achieved.

Repeatability, reproducibility, precision are all expressions of the same concept. Think of it as a grouping of bullet holes in a target, the closer they are, the better the repeatabilty. Reliability or accuracy expresses how close the result is to the true value, or whether the bullet holes are all in the bullseye.

Permit me to doubt the average mall employee has any grasp of those principles.

Having been involved in metrology most of my working life

 

Repeatability would be if a target was measured multiple time using same equipment under the same conditions and the result was the same. 

Reproducibility would be if the same target was measured with different equipment under different circumstances and the results were the same.

Accuracy is more a measure of how close a measurement is to an accepted value. 

Precision means that one can achieve the same result time and time again.

 

Most common measurements are based on comparison to know standards. 

With infrared surface measurement the emmisivity of the surface to be measured needs to be taken into account. One would hope that is the case with Paul Blart mall cop's equipment. In hospitals where they use IR equipment for checks they take measurements inside the ear where there are less variables. 

 

On my CV it says : Apprenticed Instrument Maker.

 

yes I am bored, yes i am sat at home!

 

 

 

Edited April 17, 2020 by VocalNeal

[thaibeachlovers]

On 4/15/2020 at 11:16 PM, scubascuba3 said:

i tend to be around 36.5 at Big C Extra and around 36 at Makro, i guess it's useful to see if the reading varies from day to day

I have my own thermometers ( as everyone should in their home first aid kit ). I'm 36.5 on both the digital one and the mercury one.

[tjo o tjim]

These guns just measure skin temperature, not core temperature. Even a proper calibrated thermal imager will not be able to reliably pick out people with fevers. 

[scubascuba3]

The glass thermometers are in Fascino for 45 baht

[petedk]

On 4/18/2020 at 8:18 AM, thaibeachlovers said:

I have my own thermometers ( as everyone should in their home first aid kit ). I'm 36.5 on both the digital one and the mercury one.

yes, but you can't use them when trying to enter a supermarket. I have a mercury, which I use if I think I have a fever.

 

[Captain Monday]

The  carotid artery devices are the most accurate thermometers to measure core temperature.

Saw them deployed at ICN on my last flight. Can't remember if it was contactless or not. 

 

Thermoregulation is markedly affected in patients undergoing surgical procedures under anesthesia. Monitoring of temperature is very important during such conditions. Skin temperature is one of the easy and noninvasive ways of temperature monitoring. Common skin temperature monitoring sites are unreliable and did not correlate to the core temperature measurement. 

Aim: To compare and study the correlation of skin temperature over carotid artery in the neck to that of simultaneously measured nasopharyngeal temperature in adult patients undergoing surgical procedures under general anesthesia.

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4864693/