Science by the Numbers

Collecting quantitative data in science is all about accuracy and precision. Accuracy is being as closes to the actual measurement as possible, while precision is the repetition of the same result. It can be represented by the following diagram.

precision vs accuracy slides_Page_6

In science it is important that there is accuracy and precision especially in chemistry on the atomic level, because the difference between atoms is so slim that without accuracy and precision there would be a lot of confusion and falsities among the atom and elements.  Like for example the element Selenium’s atomic mass recently changed from 78.96(3) to 78.971(8). The difference between the two is .0088 amu. The article, stated that ” For the other 15 elements, the new weights were determined through better measurements and the changes are much more subtle.” Emphasis on much more subtle. I don’t know about you but .0088 amu does not seem to be that big of a difference, but in this case it was a big difference.  An example of where this difference matters comes from this article in an experiment in 2005.   They used Silicon and Sulfur to determine the validity (accuracy and precision) of  E=mc^2. On such a small extreme the littlest things can make all the difference and can be the difference of proving or disproving E=mc^2. Also with data Scientists use significant digits. The last number in a calculation is always and estimataion. There is only so much that can be measured because of the limited tools we have.

For example, if you have a ruler with only centimeters on it and you measure a pencil like the one in the picture. You can see that is for sure 16 cm. But you don’t know 16 and what. I estimate it is 16.0 cm but in reality it could be 16.0000000000001 cm. but because there is no way to measure that , then I can only say 16 and guess its .0 over that.  This estimation helps to make the data as accurate as possible.  Post what you get for the crayon on your own to see if you get significant digits. In science All data uses significant digits, precision, and accuracy so that it can be as reliable as possible. Its all about reliable data so that the conclusion we make about the world around us are correct and repeatable.

http://dl.clackamas.cc.or.us/ch104-01/precision%20vs%20accuracy%20slides_Page_6.jpg

http://www.eduplace.com/math/mw/background/1/10/te_1_10_overview.html

http://www.livescience.com/39912-atomic-weight-changed-for-19-elements.html

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