Chapter 2. Analyzing Enzymes and Enzyme Kinetics III

Post-Lab

During lab you used the standard error as the description of variation for your data. Since standard error can be influenced by the sample size (i.e., the number of replications) it can be a less robust method for comparison.

Examine the following two data sets:

The second data set simply had twice the sample size but the same data values were used twice. Notice the effect this had on the Mean, S.D., and S.E.

Since the same data was repeated, the Mean values stayed the same. The S.D. and S.E. both decreased because when there were more data there is greater confidence in the amount of variation that can be calculated. However, notice that the decrease in the S.E. was much greater than the decrease in S.D. (10.56% decrease for the S.D. compared to a 36.75% decrease for the S.E.). This is an indication that the sample size has a greater effect on the S.E. of the data set. This may result in the S.E. being a less meaningful (i.e., less robust) method of comparison.

With that in mind, would your conclusions for your experiment be different if a more robust statistical comparison (standard deviation instead of standard error) was used?