C. Elegans worms seem to understand the importance of taking life more quietly and resting from time to time. They take it so seriously that when we analyze their individual behavior we will see periods of movement and others of rest. When we want to know what the average activity is, we must deal with understanding these fluctuations and try to reduce them.
A simple way to reduce fluctuations is to do population measurements. The movement of populations is based on the average sum of the spontaneous movement of individuals. If we take sufficient measures over time, the average of these measurements will reflect how the population is performing. As we have detailed in another post, in our system we usually use population measurements of 30 to 70 organisms / well.
On the other hand, the variability of the data can also be corrected by simple mathematical formulas. Collecting data in larger blocks of time will reduce fluctuation cycles in population and the error bars will become smaller. We will show it graphically by representing the average activity of 4 technical replicates with populations of 35 worms per well:
In these graphs we can observe that as the size of the block of time to graph is increased, the measurement becomes more stable and the error bar decreases. The result is reasonable if one considers that these error bars are due to the stochastic (random) property of the movement and to the variability among the wells, where there is no synchronization in the movement of individuals.
In this particular example the difference in error bars is not very large, but it occurs and it is important when considering a statistical analysis. Here is a chart to see more clearly what we are talking about:
As we see, errors can be reduced by at least 20% by only taking large blocks of time in our analysis.
Considering the importance of taking a more relaxed life and rest from time to time, in your next break time take advantage of reading another interesting blog.