A challenging task

While the page "Coaches - Challenges" has been present on my website for a long while, it was always bothering me with a variety of inaccuracies, as well as the inability to properly incorporate another event, when the Situation Room interferes with the game: the Video Review. Therefore I put myself to a task of comprehensive accounting of all Coach Challenges and Video Reviews dating back to 2015.

The main information about challenges and reviews comes from the Play By Play sheets. In many cases the flow is straightforward:

• There's a CHL event with the type of challenge and the challenging side
• There's the outcome in form of the timeout event by the challenging side

Unfortunately, the data is not very consistent and in many cases, lacking. Sometimes there's no CHL event, but instead a STOP event with a CHLG string. Sometimes the timeout is not there. Sometimes the challenge is attributed to 'League' - something that should only happen in the last minutes of the third period or in the overtimes. Sometimes there are two challenges, and one is missing. And sometimes even the wrong team is attributed to the challenge. While overall the NHL data is pretty steady, the challenge is the worst - probably because it involves a lot of human-contemplated input. And a lot of Video Reviews just go AWOL from that event sheet.

Fortunately, from about mid-2015 season, NHL publishes the "Situation Room Blog" - a rubrique on its site that is very scrape-able and moderately structured. Thus I was able to pick all the Situation Room proceedings since around January 2015 and parse them into a structure similar to the challenges from the PBP sheets. Then I was able to cross-compare the lists per game. That allowed me to correct quite a few challenges as well as add more challenges and video reviews.

The total tally includes:

• 885 Coach challenges from CHL events
• 264 Coach challenges from STOP events
• 30 Coach challenges from Situation Room blog
• 56 Video Reviews from CHL events
• 937 Video Reviews from STOP events
• 216 Video Reviews from Situation Room blog

Altogether 2388 events.

I consider the League Challenges equivalent to Video Reviews.

In the next blog post I'll show how they are breaking down by outcomes for each team and in other ways. I plan to add a page of challenges and reviews in the Team section of my website.

The Website - A Page A Day, Part II - The League section and the Daily Summary

Prologue
Part I

It looks like it's time to resume our Website - A Page A Day series.

PART II

The first section available on our website is the League section. It contains pages either describe statistics applicable to the entire league, rather than to a specific team, player or coach, such as, for example, the West vs East account, or the statistics go across different categories, for instance, the Warm Welcome page that is applicable to the teams as we as the goaltenders.

We'll start with the first page of this first section - the Daily Summary.

This page looks like most of the data pages of this website:

• A menu on the top (we remove the game ticker to lighten the pages)
• A section navigation on the left
• Main data pane on the right, featuring graphs and tables
• A utility menu on the bottom.

This page features the summaries applicable for today's games. This page is planned very much like an ever going work in progress, but currently only two items are featured:

The historic tally of today's coaches against each other

Our database features games from the season 1987/88 through current. Our statistics account for these games in the last 30+ years. This is usually sufficient to cover all active coaches' encounters. However we plan to integrate the remaining seventy years, from 1917 to 1986, as they became available from NHL.

The predictions for today's games by our model

We display the matches for the day where we calculate the expected number of goals by each team against its opponent, and derive the probability of a win from these expected scores.

As the rosters become available for the upcoming games, we adjust our prediction by these rosters, otherwise best-scoring rosters are used. This may change in the future. The predictions by the published rosters are marked by asterisks.

Beneath the table there is a set of useful links:

• 'Table' link that produces a pristine, unstyled table in a separate frame for easy re-use
• 'Link' link that points at the table which is currently being displayed (this one is more useful for paged and/or filtered listings)
• Tweet button that allows you to share this page on Twitter
• Like button that allows you to like this page for Facebook

Possible future additions:

• Historical browsing of previous predictions
• Elaboration of the scoring components
• Change in the win probability formula
• Your ideas are welcome!