Could anyone please help with data analysis. Briefly, I am studying how the population of a bacteria changes at different points (port 1 to port 10) within a biofilter over the course of 30 days(like a time series)

For example, if data looks like below,:

Samples:........Day 0............Day 15......Day 30

Port 1...........3.6..............4.5.........5.0


Port 10.........2.8...............2.9.........3.2

then how can I figure out whether there is a significant variation between the data sets (or as whole) from day 30 to Day 0?

Help will be much appreciated.

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    $\begingroup$ Sounds like a mixed effects model (some also use the term hierarchical model) would be appropriate. $\endgroup$ Jan 10, 2014 at 8:43
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    $\begingroup$ So, ports 1-10, each measured for 30 days? And you want to compare the ports to each other, or just how change happens for each port, irrespective of others? $\endgroup$
    – ShannonC
    Aug 26, 2014 at 20:53

1 Answer 1


Sir, In medical sciences researchers have made standardized level of control group which is normal reporting in medical term. we may compare the bacterial count. (1)Use compared t- test on per day data with mean differences and standard deviation (Pooled) or control group s.d.at significance levels(for example,5%) (2) make a frequency distribution of grouped data of 30 days three categories of above average, average, below average count of bacteria ,for example,0-10,10-20,20-30 if data is like. Show in counts cross tabulation and apply chi-square test. regression analysis of time (day1 to 30th day) and score of bacterial counts per day.


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