accuracy and reproducibilty

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makedonksa
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accuracy and reproducibilty

Post by makedonksa » Fri Mar 07, 2008 10:38 am

i am not sure can someone clarify me with these two they confuse me to hell i am only a first year student at uni

accuracy = standard deviation
reproducibilty = mean

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mith
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Post by mith » Fri Mar 07, 2008 12:09 pm

You have a scale.

You measure a block of wood and the weight comes out to be +/- 10grams each time. That's a measure of its accuracy.

The real mass of the block is reflected by scale measurements, that is your mean mass does not change each time--the scale isn't just reading off random numbers. This is reproducibility.
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makedonksa
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Re: accuracy and reproducibilty

Post by makedonksa » Fri Mar 07, 2008 12:37 pm

so therefore if you wanted a certain volume(650uL) from a pippete you would rather choose one with a lower standard deviation. eg
one might have a mean of 650UL +/- 15uL and another might have 600uL +/-2uL, therefore the second one would be your most appropriate choice becuase of less deviation in volume during consecutive weighings???

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mith
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Post by mith » Fri Mar 07, 2008 1:21 pm

The one with low SD would give you internal consistency, meaning that if it works for you once, it'll probably work again. However if it has low reproducibility, then it's probably off, meaning if you measure out 200uL, you might consistently get only 180uL on average. Therefore the values you get might only be applicable to your pipette.

Whereas the one with high reproducibility but high SD might only work some of the time, but if you average out the times it worked, you'll get a pretty reliable number.

Ideally you want both lol.
Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
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