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Jon Peltier

I thought that heat map was terrible, but all the articles citing it said it was awesome.


"I fail to find any consistent patterns in the rows."

What about the 13th of each month being a low birth day? That heatmap view is one of the few ways that draws out that fact. It seems like people may be avoiding giving birth on the 13th out of superstition. There are other ways to pull out this fact, but I thought it jumped out well on the heatmap.

While it isn't noted in the author's post, since the data comes from the CDC, I expect it's for births in the United States. It's a very important fact that should be noted on the chart because of the correlations to US holidays.

Geoff Ellis

Yes, it shows the 13th low as well as the 4/5 July and 23/26 December. Must be the US .... interesting to see if public holidays in other countries show a similar trend. One thing is doesn't show are weekly patterns, which could be achieved by highlighting each Sunday for instance.

"Alternatively, days can be ranked within each month". Rather than this (is a month interval really relevant?), why not remove the smoothed value to see the weekly trends. Another view would be to stack up the weeks on top of each other.

Just goes to show that the key to exploring data is to give the user lots of different views to explore! To do this automatically is not so straightforward, but for instance an FFT would pick out the principal frequencies and views could be suggested based on this.

BTW, I wouldn't consider this as complex data!


If the downward spikes were reliably on one day of the week (as the Thanksgiving one is) I'd suggest fifty two weeks plotted seven times, once for each week day. But the other patterns don't fall on week days, so instead I suggest two plots of fifty two weeks each, one being the median of seven days, and the minimum of those same seven days. The weekly minimum will be e.g. Christmas day whichever week day it's on.

Alternatively, a year starting on the first weekday after 1 March should allow you to line up the seven days without smearing, even in a leap year. That would also solve the problem where 1 January is getting a raw deal by being on the left with no December figures for comparison. But Thanksgiving risks being smeared a little, or doubled at least. Can't be helped.


all good points about the heat map use for this visualization. thanks for this post.

at first glance, i thought the heat map was nice. but then having seen the simple line chart, the heat map does become very one dimensional. it loses out on being able to show the significant dips/spikes, which seems to me to be one of the most important findings here.

@derek thanks for sharing your thoughts on plotting. very informative and helpful. tnx!

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