5 General notes and tips

It may be better to use the evaluation column instead of the evaluation_code column for filtering and other data operations

Different scouting conventions mean that the entries in the evaluation_code column don’t always mean the same thing. For example, a block scouted as B/ is an invasion (net touch or other violation) according to the default DataVolley conventions, but some scouts instead use B/ to indicate a block tool, and others use it to indicate a poor block back to the opposition team. When a file is read into R with dv_read, the evaluation codes are converted into strings (stored in the evaluation column) following the conventions specified by the skill_evaluation_decode argument. Using the evaluation column is therefore likely to be more robust than the evaluation_code column, especially if your code is to be used on files collected by different scouts.

For example, find block invasions by

px %>% dplyr::filter(skill == "Block" & evaluation == "Invasion")

rather than by

px %>% dplyr::filter(skill == "Block" & evaluation_code == "/")

Identifiers

There are a number of columns in the play-by-play data that are useful to identify different aspects of play

  • match_id uniquely identifies the match
  • set_number is the set number (1–5) within a match. If you want to uniquely identify a particular set (from amongst many matches) use the combination of match_id and set_number
  • point_id identifies the rally number (point) within a match. Each rally (point) begins with a serve (or rotation fault). Timeouts and other non-action points might have their own point_id, so don’t rely on point_id values being consecutive from one rally to the next. point_id values are only unique within a match (so e.g. two different matches will both have a point with point_id value of 1
  • team_touch_id identifies the touches that a team makes while the ball is on their side of the net. So a serve will have a certain team_touch_id, then the reception, set, and attack made by the receiving team will all have the same team_touch_id (different to the serve’s team_touch_id). The following block, dig, set, and attack will have another team_touch_id, and so on. team_touch_id values are also only unique within a match
  • the phase column identifies the phase of play: it can take the values Serve, Reception, or Transition. Note that a block made against a reception attack (the attack made by the receiving team immediately after receiving the serve) is considered to be Reception phase, but the dig made by the blocking team immediately after that (and every subsequent action in the rally) are Transition