Happy Pi Day! I’m **Sheila B Robinson**, aea365’s Lead Curator and sometimes Saturday contributor. If you had an internet browser open to this site today, 3.14.15 at precisely 9:26:53 am (EST) looking for today’s post to be about Pi Day, then you probably know that today is a particularly prodigious Pi Day as we have a date and time that represent the first 10 digits of pi, something that will not occur for another 100 years (OK, to be fair, another 12 hours, *then* another 100 years!).

**Lesson Learned:** Pi Day is celebrated internationally each year with deference to every mathematician’s favorite constant – the ratio of the circumference of a circle to its diameter —which is approximately 3.141592653… and has now been calculated to over 1 trillion digits! (Back in my school days, we only had to memorize 3.14.) Pi enjoys an illustrious history and you can read more about it and actually see one million of those daunting digits on www.piday.org.

Now, as we slickly segue from the consistently celebrated constant to the perpetually plagued pie chart, let’s take a moment for a 360 degree look at pie chart perspectives from a*round* the blogosphere:

We can only surmise how Cole Nussbaumer, of storytelling with data, feels about pie charts with her evocatively titled 2011 post, *death to pie charts**. *Perhaps not surprisingly, it opens with, “I hate pie charts. I mean, *really* hate them.” Nussbaumer explains, “My main beef with pie charts … is this: our eyes aren’t good at attributing quantitative value to two dimensional spaces. In English: *pie charts are really hard for people to read!”*

Pie charts receive a bare modicum of redemption from Slate in a 2013 article, *In Defense of Pie Charts* wherein author Matthew Yglesias declares (somewhat not-so-convincingly, as it’s by way of a double negative), “it’s by no means true that pies are never the right way to go.”

Back in our own evaluator neighborhood, Kim Firth Leonard, of actionable data blog stands boldly on the fence declaring, “I’m not entirely ready to abandon using pie charts in my own practice” in her 2012 post, *My love hate relationship with pie charts. And pie.*

And evaluation’s dataviz darlings Stephanie Evergreen and Ann K Emery have allowed pie in moderation with only the simplest of ingredients, of course, as elucidated in their recipe card for gorgeous graphs, the *Data Visualization Checklist* (downloadable from either of their sites).

Coming full circle (seriously, how could we not?) with a return to Pi, we can perhaps see some esoteric connections to evaluation in this fact, courtesy of www.piday.org: “As an irrational and transcendental number, [pi] will continue infinitely without repetition or pattern.”

*Do you have questions, concerns, kudos, or content to extend this aea365 contribution? Please add them in the comments section for this post on the** aea365 webpage** so that we may enrich our community of practice. Would you like to submit an aea365 Tip? Please send a note of interest to **aea365@eval.org** . aea365 is sponsored by the** American Evaluation Association** and provides a Tip-a-Day by and for evaluators.*