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| Near Record Size Meg Tooth Found. Source: See TheState.com link below. |
Here is the link if you want to see the article and a video showing the find of this huge meg tooth.
https://www.thestate.com/news/nation-world/national/article243420076.html
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In the 1950s, partly as a response to the development of radar systems, signal detection theory was developed. It was developed to measure the effect of decision strategies during situations in which a person has to make a binary decision under conditions involving uncertainty. For example, does the radar return indicate a plane or is it just clouds or noise or something else. Applying it to metal detecting, a signal might indicate either a good target worth digging, or something else.If a person is trying to detect very weak signals in background noise (for example, locating aircraft or missiles on a radar screen, or identifying a good but deep "diggable" target) the problem is to pick out the good signals from the noise (both physical and psychological). But if the signal is very faint, or the noise level is very high, the observer will likely make some errors.
Breaking it down and applying it to metal detecting, a person can make two kinds of mistakes - false positives and false negatives. It would be a false positive when the detectorist thinks there is a good signal, but it is actually a junk target, ground mineralization, background noise, or something else. A false negative error occurs when the detectorist misses a good signal. It could be a weak signal because of target depth, or the signal could disguised by background noise or ground mineralization or confused by a conductivity reading on the meter, or other things.
Experimental studies show that decision strategies can be modified to reduce false positives or false negatives. In terms of metal detecting, detectorists might decide to make sure they do not dig any bad targets, or alternatively, they might want to make sure they do not miss any good targets.
People are capable of minimizing false positives or false negatives, but not both at the same time. There is a trade-off. People who hate to dig anything but good targets, and therefore do not dig anything other than signals they are very sure about, miss more good targets, while people who hate to miss any good targets, will inevitably dig more junk targets.
You can see the two kinds of errors on the table. They are the red outlined boxes.
There are false alarms when the operator mistakenly thinks there is a good signal when there is not, and misses, or false negatives, when a good target exists but it is missed.
The upper left box indicates a good detector signal that is recognized as a good target.
The upper right box (false alarm) indicates there is no good signal but the operator (detectorist) thinks he heard a good signal. In metal detecting, that mistaken impression can be caused by a variation in the threshold tone, background noise from interference or ground mineralization, or a misinterpretation of a conductivity readout.
The bottom left box indicates a good signal that was missed or misinterpreted and responded to as no signal or noise. And the bottom right box, indicates no good signal present and no response.
So to put it in the most simple terms, the two types of errors are (1) missing a good signal and (2) thinking there was a good signal when there was not one.
I know that sounds like a lot of talk to say very little, but signal detection theory is more complex and mathematical and I tried to give just some of the basics as it applies to metal detecting.
Research has shown that people can improve their performance by adjusting their decision making process. If your priority is to NOT miss any good targets, your decision making will be shifted so you dig more (perhaps everything), and that means inevitably digging more junk targets.
If you really hate digging junk, as some people do, you might dig only when you think you know for certain the target is good. That inevitably means making more of the other type of error - missing good targets.
Of course, I've only talked about fairly extreme decision strategies: digging everything or digging almost nothing. You can adopt a more moderate decision strategy and decide to seek additional information.
Intelligent assessment of the overall situation can be used to improve your decision strategy. That is the important part. What type of error are you more willing to make under the circumstances? How willing are you to give up high value targets in order to avoid junk and other misses? That will depend upon your priorities and your assessment of the situation.
Your decision making can be shifted one way or the other. It is actually possible to make some detailed calculations of the effects of different decision strategies, but that is way beyond the scope of this post.
If you are on the side of digging everything, you will inevitably learn about many of your errors. You will see the junk you dig. But if you only dig when you think you know for certain that something is good, you will never find out how much you may have passed up. It is easy to think your decision making is perfect, or nearly so, when you only dig targets that you are very certain you know are good, but you don't find out how often you might have been wrong.
I won't get into any more detail, but think you will benefit from being aware of the different kinds of errors you can make and the trade-offs involved with different decision strategies.
I apologize for muddling this. Although I use it, it is the first time I tried to communicate signal detection theory as it applies to metal detecting to anyone else.
It can be a very useful tool for the detectorist or treasure hunter interested in maximizing dig/no dig decisions. Much math and probability theory is involved. Sorry I was only able to barely scratch the surface.
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There are many sites where you can learn more about signal detection theory.
Here is one link.
https://www.psywww.com/intropsych/ch04-senses/theory-of-signal-detection.html
Here is another that gives a good introduction.
https://www.cns.nyu.edu/~david/courses/perception/lecturenotes/sdt/sdt.html
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You might also be interested in my posts on math for metal detecting. Below is the link to one of those.
https://treasurebeachesreport.blogspot.com/2014/07/71014-report-math-of-metal-detecting.html
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Not much on the nhc map right now.
The surf will be real small for a few days.
Happy hunting,
TreasureGuide@comcast.net