Before we start, be aware. This article refers to equipment claiming to be "Scientific". It does not address some of those fakes and garbage like Spirit Boxes, Ouija Boards, and other such junk that admit to being "For Entertainment Only".. I leave that for other topics!
Many make an argument in support of using hobbyist equipment for investigation. They claim that things such as KII meters, low cost voice recorders, phone cameras, and similar devices can be used to obtain valid evidence. They use such evidence to support their claims of ghosts or spirit contact. Some even say that because we don't have a full understanding of what we are dealing with that these practices are acceptable.
These methods are not acceptable if you are doing scientific research. I would argue that because of the latter statement it is even more important to use only equipment that is reliable, and properly calibrated for any paranormal work. Consider the following scenario to understand the reasoning behind my argument.
Suppose we are attempting a task, whether it is scientific research or simply trying to prove something to ourselves. That is what many of us are trying to do. Some are attempting to reach out to, or prove, contact with the other side. Others are seeking answers to something unexplained. In either case, precise measurements are required to validate our belief. To better understand the reason why this is true, let's compare it to another task easier to comprehend. Suppose I gave you a cement block and assigned you the task of weighing it.
You have two scales, one a precision scale, the other a cheap one. You place the block on the cheap one first and it says the block weighs in at 14 pounds. You first think you have the answer, but just to be sure you put the block on the other scale. It says the block weighs 10 pounds. So now which is right? How is this different than capturing EVP on a cheap voice recorder? Is it not true both are evidence? Yes it is, but how dependable is it when they don't agree with each other?
So now you go back and weigh the block again to try to resolve the discrepancy. Again the good scale weighs the block at 10 pounds. The other one says 12 pounds this time. So you weigh it again and again. Each time the good scale weighs the block at 10 pounds while the cheap one comes in with different results each time. Twice it even agrees with the good scale, but the next time it's off again. It is just like playing your EVP for 6 people and getting 6 different interpretations of what it says. There is no resolve; the meaning is unclear.
Finally you assume, based on the above, that the block weighs 10 pounds because one scale is uniform while the other has returned various results. But to make that assumption is premature. How do we know the good scale hasn't returned the same wrong answer each time? All we know is the results are consistent, not that they are right. You get a known weight and place it on the good scale. Its weight is precisely known; it is what those of us who deal with instrumentation know as a calibration standard. It is supposed to weigh 15 pounds , but on the good scale it weighs only 12 pounds. Your good scale is out of calibration!
But you can correct that. It is apparent the scale is weighing 5 pounds too light, so with the known weight you adjust the scale's settings to where it shows the correct 15 pounds. You have just completed the calibration procedure. Now, when you weigh the block you get the weight of the block at 13 pounds. This is the calibrated, correct weight. And because the scale is consistent each time you repeat the process you will see the weight as 13 pounds. The good scale will hold its calibration.
Next you attempt to calibrate the cheap scale using the same standard weight. It weighs the standard at 17 pounds so you adjust it to 15 pounds, the weight of the standard measure. You remove the weight and put the block in its place. The block weighs 11 pounds this time. It still doesn't agree with the other calibrated scale. You go through the same process with the block and scales again, and again the weights on the cheap scale vary while the good scale weighs a consistent 13 pounds. Note that every once in a while sheer dumb luck causes the bad scale give the correct weight. But it is not consistent so you must ask, "How reliable is that?" Can you trust that scale? You do the only proper thing; Next morning the cheap scale is sitting out by the dumpster...