You guys I am so confused and this may be like an idiotic question but is it me or this a histogram? sort of symmetric? Could it still be bell-shaped if every other value goes up and down? Please help out !
It is a histogram, but it is multi-modal. Not knowing exactly what is included, I would speculate that the The leftmost pattern might be the initial group exposed to measles, and the clusters that become lower and more ragged looking as you progress to the right may be from secondary and tertiary exposures to the 1st and 2nd groups.
With a multi-modal distribution, I would not conclude that either. It you could isolate the initial exposure and remove the secondary and tertiary exposures, it might be a symmetrical, bell-shaped distribution.
I wonder if this somewhat mimics a multimodal pattern based on the traffic each day of the week and variation in the incubation period before symptoms present with a decreasing intensity as the source is identified and cleaned? Lots of specific claims but just a thought...