Question

Bead count table

‘Gold standard’ Bead concentration	My final concentration beads / ml	Class mean bead concentration	SD of class mean	CV% of class bead concentration
4.48*10^8	4.32*10^8	4.14*10^8	1.24*10^8	30%

Q1) How accurate is your bead count was compared to the 'gold standard' bead count and whether the class mean provided a more accurate count?

Q2) How precise the class bead count was and how would you improve on this precision?

Answer 1

1) Accuracy gives the measurement of agreement(closeness) between experimental value and the true value. That is the difference between the true value and the experimental value. The measures of accuracy are absolute error and relative error.

Absolute error and relative error for the bead count is done below:

So the class mean bead count gives 7.589% less value than than the gold standard bead count.

By the above results we can infer that class mean count(7.589%) does not provide a more accurate count than my bead count(3.57%), rather it gives more inaccurate value.

2) Precision gives the measure of how close the experimental values are i.e. relates to the reproducibility of results.

Lesser is the relative standard deviation, more precise are the experiment values.

Precision can be improved by:

i) Proper and frequent calibration of the instruments used in the experiment like volumetric flasks, burettes, etc.

ii) Apparatus used should be properly cleaned before using and it should be in a functioning condition.

iii) By taking the measurement multiple times.

iv) Most importantly by doing the experiment very carefully.