Weight And Volume Flashcards
(8 cards)
How do you know you balance was working the day you weighed this item
By verifying that the balance passes the performance checks prior to use
What is uncertainty of measurement
A statement about the variability in the measuring process which accounts for various environmental factors that could influence the measurement such as the type of balance
Why do items on your report have different uncertainties
This can be due to several factors. Different types of balances have different uncertainties associated with them, what technique is used to obtain that measurement, or if weights are added together
How do you come up with this uncertainty of measurement
They are calculated into a budget table that is evaluated annually. This budget table accounts for different aspects such as different analysts, different equipment, and environmental conditions
What does “the uncertainties of all reported numerical measurements are expressed at the 95% confidence level” mean
It means that I am confident that the true weight of the item would fall into the reported range 95 times out of 100.
If you were to measure my height 100 times you would not get the same answer every time but you wouldn’t say that I am 8ft or 4ft tall
Why is it not at the 99% or 100% confidence interval?
95% is the common industry standard that most laboratories use. A confidence interval of 100% is not possible.
Does this mean that you are only 95% confident that this sample contains methamphetamine?
No the confidence interval only applies to the weight of the sample.
How sure are you that this sample contained methamphetamine
I cannot quantify my personal certainties however I followed proper procedure the data supports my conclusion
