How much accurate are the instruments that we use in measuring, during experiments?
So how can we be sure that the value we get could be accurate or not? Is science more of agreement than Prof? Get some information using this link.http://resources.metapress.com/pdf-preview.axd?code=h1q3778238488455&size=largest
Monday, February 23, 2009
Subscribe to:
Post Comments (Atom)
Comments
6 comments:
Chilot,
You are right to point out that precision and accuracy are very important in scientific measurement.
Can we open up this topic to the experiences of many other students - has there been any discussion in chemistry or physics or biology classes about uncertainty and error analysis?
i do agree that the accuracy of the mesurments is not exact. even we can see that measuring 50cm3 of water in a 50cm3 beaker and 50cm3 measuring cylinder is not the same, why???
how can unceranity be different for the the same volume measurments(for instance 50cm3 beaker and 50cm3 measuring cylinder).
The measurements we get in scientific (let me say Biology cause that is my area of interest) experiments are just close to the real values,not exact.For example in Biology I can weigh a bean seed on a weighing balance and get a value like this 17.7g but is this the exact value? Simply not,it is just close to the real value.The real value itself might have been 17.73343...g but the apparatys was made to give those decimals so what do we do?
In this case the error of uncertainity will be (+/-0.1) dont ask me how because I don't want to get into maths.
However in life there are no accurate apparatus and not matter how will try,we will never get exact values.The world is not exact(Limitation of sense perception)
There are some interesting differences here within the natural sciences.
For example, in biological systems, data tends to be more variable than in the physical sciences. This means that in biology we are often more interested in measuring this natural variability rather than the uncertainty of the instruments we might be using to make the measurements, because the former is much larger (and therefore more significant) than the latter.
Any insights here into knowledge in the natural sciences?
Hmmmm...Mr Kitching's comment seems to oppose mine
Hot Ice,
I don't think that my comment opposes yours. I am merely pointing out that in some circumstances - particularly when we are dealing with complex systems such as those commonly found in biological sciences (such as ecology, where there are many variables that cannot be rigorously controlled), or perhaps more pointedly in the human sciences, the true variability in the data can dwarf the possible uncertainties arising from the measuring instruments.
Your example concerns a relatively simple type of measurement - that of mass. If you were to measure, say, the masses of 100 bean seeds, you might well find that the variation in their masses was such that the fractions (or decimals!) of a gram that constitute the uncertainty arising from the weighing scale end up looking miniscule and hardly worth considering.
Now if you were finding the mass of something in a chemical or physical context, this uncertainty might be much more important, relative to the variability in the true data, and so you would want to take it into account - possibly even to propagate it through whatever calculations you needed to do.
Post a Comment