Standardizing by a mean?

#1
Greetings all,

I have been approached by a colleague with what appears to me to be a tricky question. I'll try to be as succinct as possible: They are measuring heart rates of mice and they wish to compare two incubation treatments so they have a data set, i believe which contains three measurements taken from each individual in treatment 1 (to correct for measurement error; these I presume will contribute to a single average) on day 1. They then have values of measurements of heartbeats taken from individuals in treatment 2 on day 2. I believe to standardize across days (instead of just blocking... which would have been nice). They took measurements on a sort of standard (I'm assuming it was say 10 individs not associated with either treatment sampled on the different days).

Moral of the story is I'm not sure what the best way to go about this without wasting data would be. Should I subtract all treatment values first by the mean of the standard for that day then do a two-sample t-test? Since they're not independent I can't really toss them in as controls. I don't believe there is any way to do an ANCOVA because the correlated measurements (to standardize for temp) don't match specifically to any individual treatment measurements. Perhaps I should weight each treatment by the mean of the standard? I know little about weighting and it seems somewhat black box to me...

Perhaps there is a standardized way of approaching this problem that I've just been missing but it seems to me to be the classic case of why we set up experimental designs with blocks.

Cheers!
 

Dason

Ambassador to the humans
#2
Would it be possible for you to post what the data looks like? Possibly a few lines from the data itself? I'm having a hard time visualizing what you're trying to explain.

Do you have all the observations or do you just have the means for each mouse?
What do you mean by "they took measurements on a sort of standard"? Does this just mean there was a control group to compare against? What does the data for this "standard" look like?
 
#3
Sorry for the ambiguities, I have no idea what the data looks like, we're supposed to have a formal meet tomorrow I'm just getting a head start. I'll have all three observations for each mouse but they aren't interested in any repeated measures and they would just be pseudoreplicated which is why I'm guessing they'll just want to take the mean to reduce some measurement error. I'm not sure what the standard group looks like, lets say it's just 10 completely different individuals sampled 3 times on day 1 and again three times on day 2.