A while back I trotted out a measure called a shot volume index (SVI) for men’s Division I basketball. At the time I said the index could be viewed as the number of FGAs a team would record in 100 possessions marked by average shooting accuracy and zero free throws. This quite naturally elicited responses stating that the metric ignores free throws.

Maybe it’s a Kinsley gaffe to say this, but the stat in question actually ignores both FTAs and FGAs. Rendering the output as FGAs over 100 possessions was a suggestion for the scale on a new thermometer.

The shot volume index runs on turnovers and offensive rebounds.

Shot volume index (SVI)

(100 - (100 * TO%)) + (OR% * (0.561 * (100 - (100 * TO%))))

An otherwise enigmatic 0.561 represented the likelihood of a given shot attempt being a miss. Straight FG% rears its head after all. (Well, 1 – FG%.) For the record the mid-2020s men’s D-I number is closer to 0.559.

Alternately, we can count actual shots. Seems intuitive enough.

“Easy hack” method

(FGA + (0.475 * FTA))/possessions

While adjusting for tempo, this approach counts attempts from the field and adds the product of shots from the line and a free throw multiplier.

For a commendably refined upgrade in this same “counting shots” category of metrics, I heartily recommend the method found at Hoops Insight.

Possibly we can think of all of the above volume measures as belonging to two different families of stats. There’s the inferential method (WHACKS, SVI) and there’s counting shots (easy hack, Hoops Insight).

Despite having very different backstories, these two families coexist in serene evaluative accord when it comes to producing rankings. Indeed, compared to those Hatfields and McCoys known as resume metrics, the field of shot volume studies appears as peaceful as a Swiss canton.

We can throw a stick at just 13 team-seasons out of 156 and pick off the top 10 across three very different volume gadgets.

Three measures of shot volume
Rankings of top 10 team-seasons for volume, KenPom years 2023 and 2024

Major-conference games only
                                  Hoops     easy
                         SVI     Insight    hack
Texas A&M      2024       1         1         1
Houston        2024       2         2         2
NC State       2023       3         7         4
Florida        2024       4         3         3
Illinois       2024       5         5         7
Purdue         2024       6         6        15
UConn          2024       7        12        12
St. John's     2024       8        10         5  
Tennessee      2024       9         9        14
Vanderbilt     2023      10         4         6
Kentucky       2023      12         8         8
Pitt           2024      15        17         9
Xavier         2024      17        13        10

Naturally rankings aren’t everything. If we had wanted to predict offensive efficiency in major-conference play over the past two seasons, for example, we would have been better off (barely) using straight turnover percentage instead of our easy hack for shot volume. The hack can locate teams within the shot volume hierarchy but it sheds relatively little light on how good those offenses really were.

Conversely a shot volume index takes a whack at both tasks. The index ranks teams by volume and also correlates pretty well with scoring.

Shot volume measures and four factors versus points
Correlation coefficients for points per possession

Based on major-conference games, KenPom years 2023 and 2024
                           
                        Correlation
FTRate                     0.149

OR%                        0.376

Easy hack                  0.489

TO%                       -0.517

SVI                        0.695

eFG%                       0.799

Possibly the two families of volume stats are pursuing overlapping yet distinct aims. One family seeks a correct shot count. The other wants to know which offenses are most likely to outperform a given level of shooting accuracy.

Purely as a narrative device a shot volume index dovetails nicely with a Whig history of offense over the last three decades as told by KenPom stats. As late as 1999 D-I men’s teams as a whole were still turning the ball over 23 percent of the time. Since then turnover rates have declined steadily along with offensive rebound percentages.

Turnovers are a weightier factor than offensive boards (see above), so the net result of two seemingly countervailing trends has been a rising shot volume index. This growth in volume has lifted offensive efficiency across the sport despite the fact that shooting accuracy this season is identical to what it was in 2019. At this writing D-I’s 2025 numbers for offensive efficiency and the SVI are both at the highest levels seen to this point of any season in the KenPom era.

A shot count’s relationship to points can be more fraught. Certainly it’s an unalloyed benefit for an offense to avoid possessions with zero attempts from the field or the line. Past that things become problematic. A team missing two shots from the field and failing to get the second rebound, for example, hasn’t recorded a better outcome than if the offense made its first attempt.

A volume index wants to avoid this messiness entirely by holding accuracy constant. The number produced by such a “platonic” bit of math isn’t going to be a shot count, exactly, and quite possibly that’s unfortunate coming from an item with “shot volume” in its name. Such a number will instead estimate how well your turnover and offensive rebound rates translate into scoring opportunities in an eFG-neutral setting.