#What the Positions tab is
Stats > Positions shows every decision from your analysed matches as a board, good plays as well as mistakes. Each board is drawn as the player who decided saw it, with their side at the bottom, the move they played and the best move drawn as arrows.
A decision is listed once an analysis of its match has finished. When a match has several analyses, the deepest one from our own engine is used; an imported analysis (eXtreme Gammon, GNU Backgammon, BGBlitz) is used only when there is nothing else.
#Where your equity goes
The Overview tab has three panels built from the same decisions, each under the page's filter, for your own play or your opponents':
- Equity lost by error size: how many inaccuracies, errors, blunders and worse you made, and what share of your lost equity each size accounts for. Many small errors and a few large ones call for different work.
- Cube decisions, split by what the right action was. "When the right action was Double, you got it wrong 2 times (25%)" counts missed doubles against every position where doubling was right; wrong takes are counted against the positions where passing was right. The bar beneath says whether your cube errors lean too aggressive (early doubles, doubling when too good, wrong takes) or too passive (missed doubles, wrong passes).
- The dice: your luck per roll beside what your decisions cost you per decision, and your jokers (rolls worth 0.3 of a point or more to you) and anti-jokers (rolls that cost you as much). Only rolls whose luck was measured count: a match imported from another program carries none.
- By match length: your error rate and XR at each match length you play.
Every count is a link: it opens this tab with that panel's rows. The panels add up decisions on one scale; decisions analysed on another are named above them rather than mixed in.
Two more views sit beside them. Matches by level counts your matches at each XR level, on eXtreme Gammon's PR labels, which one overall number hides: twenty matches at Advanced and twenty split between World Class and Casual average the same. The XR headline names its level too.
The accuracy and XR charts draw a line pooled over a window you choose: a day, a week, a month, every 10 matches or every 500 decisions. Pooled means the window's decisions are counted together, so a short match weighs less than a long one. A window that is still open (this week, this month, or the last few matches short of a full run) is left off the line unless you tick Show the unfinished window, because a handful of matches drawn as a full window looks like a trend. The dots are every match either way.
#Topics
Stats > Topics ranks where your equity goes. A topic is a kind of decision cut one way: checker or cube, a phase, the structure you had, the score, or the cube role (doubling or taking). Each row shows how many decisions of yours it holds, your error rate against the rate the rest of your play predicts for it, the equity lost per 100 decisions and in all, and your costliest decision in it. The count opens those positions here, and Practice starts a session over them.
Topics read your last 30 matches under the Overview's filters, your own decisions, and count an error from 0.040 on. A topic is ranked by equity lost per 100 decisions; a topic with fewer than 30 decisions is listed apart, not ranked yet. Weak spot marks a topic only when your error rate in it is higher than the rest of your play predicts, by more than chance explains, after allowing for how hard that kind of decision is for every player. The same test gives the Overview's weak spots.
Checker events (hits, made points, broken anchors and the rest) are listed below the topics: how often the best play did each, how often your play missed it or did it where the best play did not, and what that cost. They are described, never marked weak, because one decision can hold several events.
#Presets
The list on the left is a set of ready-made filters: mistakes by size, cube mistakes by kind (missed doubles, wrong takes, wrong passes), the opening rolls, checker-play themes such as missed hits or anchors broken too soon, and the same decisions grouped by structure, phase and match score. Each shows how many positions it holds under your current choice of whose decisions and matches, and the search box above them (/) finds one by name. Click a preset to replace the filter, or Shift-click it to add its chips to the ones you have.
A preset marked ◐ names its own answer: in Missed hits the answer is always "hit". It is practised through its neutral parent, mixed with positions where the answer was different, and the bar at the bottom says so before you start. On Standard and Pro, Save as preset keeps the filter on screen under a name, listed under My presets and as a deck in Practice.
A preset that names a verdict, like Missed hits, only lists plays that lost at least an inaccuracy. Without that floor, "missed" would also catch plays a hair behind the best.
#Filters
Every preset is a filter, and so is everything you choose above the boards:
- Whose: My plays (the default), Opponents', Both sides of the matches you played, or the Whole library, including matches you hold but did not play.
- + Position, + Error, + Cube, + Race, + Dice, + Match and + Saved each open the filters of that kind: phase and structure, error size and kind of decision, the cube action, the race, the roll, the score and match, and your saved positions.
- Events, under + Position: pick an event (a hit, a made point, a broken anchor) and a verdict, then Add. Did means your play and the best play both did it, missed means only the best play did, wrong means only your play did, and avoided means it was possible and neither did.
Show in Positions on a match's analysis summary, the positions icon on a match list row, and Show positions on a selection of matches open this tab narrowed to those matches, shown as a chip.
The filter lives in the page address, so a bookmark or a shared link opens the same result. Each active filter shows as a chip; the cross removes it. The line above the boards says how many positions match, the equity they lost and how many matches they come from; when nothing matches, it names the chip whose removal would show the most. Grid or List, Before or Arrows (the play made dashed, the best solid) and the card size are remembered on this device.
#The pills on a board
Under each board are up to four pills, always in the same order: the phase, the structure of the player who decided, the events of the play, and for a cube decision what happened with the cube. An event pill carries its verdict in words and a symbol: ✓ did, ○ missed, ✗ wrong.
#Different scales
Equity lost by our engine and equity lost by another program are not on the same scale, and neither is an analysis that did not record which scale it used. The tab lists them all, and says so above the boards when a result mixes them; the buttons there narrow the result to one scale at a time.
#Walking through
J and K move along the boards. Click one, press Enter or W, or use Walk through in the bar at the bottom to open the walk-through: the position larger, the move played against the best, what it cost, the gap to the next best move and every pill. Open in the match goes to that decision in the match analysis. The arrow keys step through the result, loading more as you reach the end; Escape closes it. Practise these (P) starts a practice session over the same filter. See Keyboard and controls.
#Picking positions for a deck
On Standard and Pro, positions can be picked by hand and kept as a deck of their own, in the order you picked them.
- Pick a board with the box in its corner, or press X on the selected board or in the walk-through. Hold Shift to pick every board between it and the last one you picked. Once anything is picked, a click on a board picks it too.
- The box beside the count picks every board on screen, and then offers to pick all the positions the filter found.
- Picks stay while you change the filter, so one deck can take six missed hits from one preset and four bear-offs from another. Clear (or Escape) drops them.
Add to deck in the bar at the bottom adds them to one of your decks or to a new deck named in place. The same position from two matches goes in once, a forced play is left out, and the message says how many of each. The deck is a study, so it is listed under Practice > Decks and opens in Study, where its positions can take notes.
A deck keeps the positions it was given. To keep a whole category up to date as you play, save the filter as a smart deck instead; when everything a filter found is picked, Add to deck offers that too.