# Experiment design - (Apr/10/2012 )

I have two questions:

1) Do standard curve need error bars? Let say for BSA standard curve, for each concentration I did 3 replicate, I find the mean and SD and plot the linear graph with error bars.

2) For Lowry assay, or other protein assays, do I need to do interday and intraday experiment? For example, in each experiment I run five replicates and I find the mean of the sample. I conduct 3 independent experiment (each with five replicate). At the end of the day I will have 3 mean values from 3 independent experiments. The final value that I will report is the mean from the means of the 3 independent experiment.

I know this is the right way of experimental design, but never read the details of experimental design for simple assay like Lowry assay. Please let me know if I do not need to follow this way for Lowry assay.

Thank you

to 1) yes, with error bars but as SEM, not as SD

Inmost sun on Sat Apr 21 14:27:10 2012 said:

to 1) yes, with error bars but as SEM, not as SD

Could you please explain why you use SEM not SD for error bars?

2) Yes, you can perform triplicate of BSA each independent experiments as a standard tube and calculate your samples based on the average of these tubes.