Units, The Language of Forensics and Science

Whether you are doing a qualitative or quantitative experiment, you need to be able to express what you found.

Quantitative science is being able to say how much of something you found. For example, patient X had 15 ppm of cocaine in his blood stream.

Qualitative science is being able to say whether you found something or not. For example, patient X had cocaine in his system.

Why would you need units of measure to express the results of an qualitative experiment? Because you need to know if the result you found is above the minimum detection limit and thus is a usable finding. If your instrument cannot be reliable below 10ppm, then you cannot say for sure that a substance is present below that amount. You can say the test was inconclusive, or you can redo the experiential at a higher concentration if possible.

Being able to express amounts is very important, below I have made a chart that explains the different units and what they mean in relation to each other.

In my experience as a scientist, the people to know the differences between the units, can express them and calculate them are great scientists.

It will save you a lot of time and energy to print out these charts and quickly be able to do calculations back and forth. Then you will be a great, efficient scientist.