I am confident that you are intelligent enough to know that if the question is what are the variables, the answer will explain what the variables are rather than to provide a definition for variables.
But the answer did not explain anything. It simply described "variables" as "what we don't know."
Much of science does describe variables. That is what many formulas are used for: to describe variables. The inverse square law of gravity told us that gravity
varies according to the mass of the bodies and the distance between them and gave us a formula for calculating the gravitational force between any two bodies no matter what the sizes and no matter what the distance between them. Gravitational force varies; it is a variable. But it is a well-known variable and well-understood. We know how to account for it, even better now than when Newton first formulated the inverse square law.
And that is another point. Newton's law, though good, was not fully accurate. Sometimes, using the formula told you exactly where a planet would be. But sometimes, the planet was not where it was expected to be. It wasn't far away, but it wasn't exactly where the formula said it should be either.
It was clear that something was not quite right with Newton's inverse square formula, but no one knew exactly what for a long time. That is an example of a unknown variable.
Then Einstein figured out the problem, and now we have an even more accurate way of keeping track of gravitational forces.
A key point here is that the unknown variable that Newton didn't and couldn't account for did not make his work either biased or useless. Most of the time, for simplicity, Newton's formula is still used. But when greater accuracy is needed, Einstein's work is used.
So variables are not necessarily what is unknown. Therefore when you say scientists are not accounting for variables, the natural question is "which variables are they not accounting for?"
And we also need to ask, does not knowing some variables really make the current work biased or useless. It is possible to achieve a high level of accuracy even when some factors are unknown.
So if you are claiming that some scientific conclusions are hugely inaccurate, there needs to be a basis presented for that claim. What would make that conclusion hugely inaccurate?
All the while, there is that pesking 1/4 that we didn't know existed and we didn't allow as a variable into our calculations that is staring us in the face, but we ignore it because we have already devised truth.
Actually, scientists have a very simple way to get around this problem. It is "Use more than one way of measuring whatever you are measuring."
So scientist A has a yardstick short by 1/4 inch and doesn't know it. But scientist B has a metre stick. And scientist C is using laser technology. And scientist D is using the odometer on his vehicle. When A's answer does not agree with the answers B, C, and D all get, they decide to check out what is wrong with A's measuring tool, find out it is too short, and correcting for the missing bit, determine that A had the right answer too.
That is the problem science has with variables, it ignores the things that we don't know in exchange for calling it truth.
Be specific. What things in particular do we not know that we need to know before we can get good scientific conclusions. In particular, in respect to the age of the earth or anything dated as too old to be consistent with a young earth.
Who sets the laws of nature?
Presumably God, since the laws of nature are derived from the properties of created matter. And it was God who created it with those properties.
How do we know what the laws of nature are?
Through the study of nature, especially its repetitive features and patterns.
Who defined those laws for us?
Each law is defined by the person who proposes it. In effect, that person is saying, "Every time I see A, I also see B, and as A varies, B varies with it in a predictable pattern." Then usually in a short mathematical equation, they set out the relationship of A to B.
If other scientists confirm that there is no known exception to the observation, it is accepted as a "law". Even more so, if they can find a property of nature that explains why the law must be what it is.
That is what made Einstein's work on gravity superior to Newton's. Newton described a pattern he had seen and as more and more scientists studied gravity, they saw the same basic pattern and agreed he had found a law of nature. But all they could do was describe its effects. They couldn't figure out what caused the effects they saw. Einstein was able to show that the law of gravity was produced by certain properties of the material universe.
So now we have not only a repeated observation with no known exceptions, but also a reason for those observations rooted in creation itself.