How stars work
thecrag.com uses a star system for routes in their publications.
Stars are community rated and are derived from user feedback. No individual can control the star rating for a particular route.
This document covers the following topics:
- Stars calculation
- User grade contribution
- Publisher grade contribution
- Quality Ratings
- Quality Score
1. Stars calculation
Route stars are assigned by the system according to the following rules:
- Star ratings come equally from ascent quality rating, user provided star rating and publisher star rating.
- For ascent quality we have a one user one vote policy. This means that if you climb a route several times then we will only take the last rating.
If a route has no stars then this does not mean that the route is not worthy of stars. It could just mean there have not been any ascents to assess the stars.
2. User grade contribution
When a user makes a grade contribution they may include stars as textual stars. For example their contribution may be "5.12**", in which case the system will work out the user thinks it is a 2 star route. Note that when inputting stars, they are simply added to the end of the grade as plain text.
You may make your own grade contribution when you:
- Create a new route; or
- Update an existing route.
Note that you can update your grade contribution at any time. Also there may be multiple user grade contributions for a particular route. User grade contributions are shown on the route page.
If you are the only person to have entered stars as part of a grade contribution and there are no ascents then the route will adopt your star rating. In otherwords when you first create a new area all the stars will be what you create, and as people start to log ascents these stars will be adjusted to the genuine community sentiment.
3. Publisher grade contribution
You may cite the grade and stars from a particular publication. It's our policy to only allow citing of grades from a particular publication if the publisher has expressed an interest to do so. When you create or update a climb you can cite the publication by clicking the 'Cite Publication' button. You will be asked to choose from a list of configured publications. If the publication is not there then you may not cite it.
Publisher contributions are listed along side of user contributions in the route page.
Publisher contributions for stars are given more weight because they are published documents.
If you are a publisher and wish to make your guidebooks citable on thecrag.com then contact us. The publication will also be promoted in the index.
4. Quality Ratings
When a user logs an ascent they are given the option to rate the route with one of the following:
- Don't Bother
- Good -
- Very Good -
- Classic -
- Mega Classic -
Combining the ratings from multiple ascents you can get an overall feel for what the rock climbing community think of the route. For example the graph below shows combined quality ratings from for routes (from left to right: 245 ascents from a route, 139 ascents from a route, 155 ascents from a route and 127 ascents from a zero star route.
In order to work out when a route changes from say a two star to a three star route we quantify these graphs into a single number called Quality Score (see below) and define thresholds for one, two and three star routes.
5. Quality Score
The Quality Score is a single number out of 100 to quantify all the user quality ratings. To calculate the Quality Score we add up each of the quality ratings in a 0-6 scale (Crap being 0 and Mega Classic being 6) then divide by the number of quality ratings and normalise to 100.
For example if the users have made three quality ratings of Good, Good and Very Good then this would be 100*(3+3+4)/6*3 = 56 Quality Score. As more user rate a route the more reliable the Quality Score becomes. If there is less than three quality ratings we do not calculate a Quality Score.
The final thing you need to know is how we determined the Quality Score thresholds for one, two and tree star climbs:
- maps to a Quality Score of 75.
- maps to a Quality Score of 58.3.
- maps to a Quality Score of 41.7.
In order to know which is the better route within a particular star group we also show the Quality Score in the tooltips as you hover the mouse over the stars. For example hover the mouse over the following stars .