Hello everyone,
I am quantifying Ca2+ waves in pericytes and I am interested in the number of waves in the quantification period and/or their frequency. The problem is that my quantification periods are quite short 20-200s, and I typically get 1-3 waves in the period, so the frequencies are low. I get different results in terms of significance depending on I am taking number of waves in the period or the freqeuncies. That is if I take the number, it is significantly different between the two periods of same length, but if I take the frequencies in the same period they are not significantly different. Which is the correct parameter to use in this situation when the waves are so few?
Best regards, Olga
It is not quite clear waves of what kind you are measuring - fluorescence or current. If your quantification period is 20-200 s and you believe it is short, why don't you make them 10 times longer? As a result, more waves will fit into one quantification period and thus improve your statistics.
I am measuring the fluorescence. I can't make the period longer because I am measuring simultaneously the tone changes of the blood vessels and I need to quantify waves only in period when the vessel contracts. So if the contraction is short my quantification period for the waves is also short.
I'm trying to figure out the source of your problem.
1. Are frequencies of your waves varying a lot from measurement-to-measurement?
If it does, your statistics will be bad in any case no matter how do you do your measurements.
2. Can you use for your measurements (and for statistics further) only half of period?
1. From 0.007 Hz to 0.09, average in the group 0.026, stdev 0.01.
2. The half of the period is not enough because the average number of waves per period is 2-3, so taking only a half will leave only 1 wave...the thing here is that the waves are quite long and not so many in the period. That's also why frequencies are low.
1. OK, 0.02+/-0.01 does not look good. And what is the n for this particular values? What is the source of such variability? If you look at your raw data and measure the length of periods, say 5 or 7 of them during one experiment, are they varying a lot?
If so, then you have no other choice but collect more data, so that your statistics would be less ugly, because the source of this variablity is the nature of your Ca waves, and you most likely cannot control it.
2. If your waves are pretty reproducable withing one experiment, then you can probably measure the slope of your wave at inflection point and use this value to derive a frequency. Again, look at your raw data and get an idea where this variability comes from
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