- P Values are not Error Probabilities (PDF) — In particular, we illustrate how this mixing of statistical testing methodologies has resulted in widespread confusion over the interpretation of p values (evidential measures) and α levels (measures of error). We demonstrate that this confusion was a problem between the Fisherian and Neyman–Pearson camps, is not uncommon among statisticians, is prevalent in statistics textbooks, and is well nigh universal in the pages of leading (marketing) journals. This mass confusion, in turn, has rendered applications of classical statistical testing all but meaningless among applied researchers.
- Breaking the 1000ms Time to Glass Mobile Barrier (YouTube) —
See also slides. Stay under 250 ms to feel “fast.” Stay under 1000 ms to keep users’ attention.
- Modern Methods for Sentiment Analysis — Recently, Google developed a method called Word2Vec that captures the context of words, while at the same time reducing the size of the data. Gentle introduction, with code.
From design processes to postmortem complexity, here are key insights from Velocity Europe 2014.
Practitioners and experts from the web operations and performance worlds came together in Barcelona, Spain for Velocity Europe 2014. We’ve gathered highlights and insights from the event below.
Managing performance is like herding cats
Aaron Rudger, senior product marketing manager at Keynote Systems, says bridging the communication gap between IT and the marketing and business sectors is a bit like herding cats. Successful communication requires a narrative that discusses performance in the context of key business metrics, such as user engagement, abandonment, impression count, and revenue.
How NoSQL databases scale vertically and horizontally, and what you should consider when building a DB cluster.
Editor’s note: this post is a follow-up to a recent webcast, “Getting the Most Out of Your NoSQL DB,” by the post author, Alex Bordei.
As product manager for Bigstep’s Full Metal Cloud, I work with a lot of amazing technologies. Most of my work actually involves pushing applications to their limits. My mission is simple: make sure we get the highest performance possible out of each setup we test, then use that knowledge to constantly improve our services.
Here are some of the things I’ve learned along the way about how NoSQL databases scale vertically and horizontally, and what things you should consider when building a DB cluster. Some of these findings can be applied to RDBMS as well, so read on even if you’re still a devoted SQL fan. You might just get up to 60% more performance out of that database soon enough. Read more…
From the lure of work that matters to building your own device lab, here are key talks from Velocity New York 2014.
Practitioners and experts from the web operations and performance worlds came together in New York City this week for Velocity New York 2014. Below you’ll find a handful of keynotes and interviews from the event that we found particularly notable.
Mikey Dickerson: From Google to HealthCare.gov to the U.S. Digital Service
“These problems are fixable, these problems are important, but they require you to choose to work on them” — Mikey Dickerson looks back on what it took to fix HealthCare.gov and he reveals his reasons for joining the U.S. Digital Service.
High-performing memory throws many traditional decisions overboard
Over the past decade, SSD drives (popularly known as Flash) have radically changed computing at both the consumer level — where USB sticks have effectively replaced CDs for transporting files — and the server level, where it offers a price/performance ratio radically different from both RAM and disk drives. But databases have just started to catch up during the past few years. Most still depend on internal data structures and storage management fine-tuned for spinning disks.
Citing price and performance, one author advised a wide range of database vendors to move to Flash. Certainly, a database administrator can speed up old databases just by swapping out disk drives and inserting Flash, but doing so captures just a sliver of the potential performance improvement promised by Flash. For this article, I asked several database experts — including representatives of Aerospike, Cassandra, FoundationDB, RethinkDB, and Tokutek — how Flash changes the design of storage engines for databases. The various ways these companies have responded to its promise in their database designs are instructive to readers designing applications and looking for the best storage solutions.
Guidelines to maximize, allocate, and use resources strategically
Step one: Build your case
Before you can instill a culture of performance, you first need to demonstrate the value of strong web performance to your colleagues and superiors. To do that, you must build a case based on business standards that everyone can relate to, specifically by demonstrating the clear link between web performance and revenue. Calculate how much revenue you would lose if your site was down for hours, or even minutes. Ask how much time IT spends fixing problems when they could be working on other issues. Figure out what your competitors’ web performance is like and how yours compares (if it’s better, you have to keep up; if it’s worse, it’s an opportunity to take advantage of their weakness).