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Shooter Accuracy & Consistency

Where your shots actually land, and whether the problem is aim or spread. They look the same on the field and need completely different fixes.

Inputs

For each shot, record how far it landed from the center of the target.Right and long are positive,left and short are negative. A shot dead center is 0, 0.

1
2
3
4
5
6
7
8
in

How far off center a shot can land and still score.

Results

Shots on target

—%

What is limiting you

—

Average miss

—in

How far the group sits off center.

Group sits

—

Spread around the group

—in

Typical distance of a shot from the group's own center.

Group size

—in

Widest gap between two shots.

Hit rate if you re-aimed

—%

Shots recorded

—

Where your shots went

Where your shots went
6 in

Every shot you typed in, plotted where it landed, with the goal as the ring. The cross is the middle of your own group. Widen the ring and watch the hit rate climb: if a small change in the ring changes a lot, the spread is what is holding you back, and if the whole group sits to one side, aim is.

How this is calculated

A shooter that misses can be wrong in two independent ways, and the fix for one does nothing for the other.

Accuracy and precision are not the same

  • Bias is where the group sits. Every shot landing six inches long is a shooter that is consistent and aimed wrong. That is the good problem: adjust the angle, the speed, or the target point and every shot moves together.
  • Spread is how tightly the shots cluster. Shots scattered around the target are a shooter that is aimed correctly and cannot repeat itself. No amount of re-aiming fixes it.

The page separates them by computing the average landing point and the scatter around that point, rather than around the target. Both come out as distances in inches, so comparing them is meaningful, and whichever is larger decides what to work on:

  • Bias larger than spread: re-aim. The "hit rate if you re-aimed" figure is what you would get with the same shooter, perfectly aimed.
  • Spread larger than bias: re-aiming barely helps. Consistency comes from steadier flywheel speed, repeatable ball position, firmer structure, and consistent compression.

Why the re-aimed figure is worth knowing

It puts a ceiling on what aiming can buy you. If your current hit rate is 55% and the re-aimed figure is 58%, then aiming is not the problem and three days spent on the aiming mechanism will win you three points. If it is 90%, aim is the whole story.

Recording it

Shoot from one fixed spot with the robot in a repeatable position, mark where each shot lands, and measure from target center. Ten shots is a usable start and twenty is much better. Bounces count where they first land, since that is what the shooter did.

Sources & assumptions

No VEX data is used. Everything comes from measurements you take, so there is nothing here to go stale between seasons.

The re-aimed hit rate assumes the group can be moved onto the target without changing its shape, which holds for small aim corrections and less well for large ones. Distance changes usually alter spread as well as position.

Treats a hit as landing within the target radius of center, which is a circle. A goal that is not round, or that catches shots arriving at an angle, will not match this exactly.

    Every source the site uses, and when it was checked

    Save this run, and compare

    Keeps what is on screen so you can change something and see both sides of the change. Saved in this browser only, never uploaded.

    Make a notebook page

    Turns this calculation into a dated engineering notebook page: the setup, data, results, figures, working and sources, numbered and cited. You add the goal, the decision and the reflection in your own words, plus photos and sketches. Print it, paste it into Google Docs, or download a Word file or slides.

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      Our own layouts

      A layout remembers how a page is set up: its type, its system, which parts print and which of your tables it uses. It never remembers a word, a number or a photo.

      Your team kept on this device
      Add someone to the team list
      Your words never written for you

      These are the parts a judge or teacher reads to see your thinking, so the page leaves them to you. Leave a box empty to get lined space for writing by hand. Start lines with "- " for a list. The notes under each box only count and point things out; they never change what you wrote.

      Rough notes

      Rough notes

      Rough notes

      Rough notes

      Rough notes

      Rough notes

      Rough notes

      Rough notes

      Rough notes

      The word counts can be measured against a target your team sets on My notebook. The reading level is Flesch-Kincaid grade level = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. Syllables are counted by vowel groups, so the grade is an estimate of the school year the writing reads at. It says nothing about whether the writing is any good.

      One part at a time, with a clock. At the end of practice, while you remember it.
      How you tested your details

      Fill in what applies. These print as a small table under the method.

      Before and after

      Compare this calculation with a run you saved earlier on this tool (under “Saved runs”). The page shows what changed and by how much.

      A line through the data from your recorded table

      Pick two measured columns from the same table. The page plots them and draws the least-squares line, only across the range you measured.

      Robot log a CSV from the robot's SD card

      Load a CSV your robot saved. Pick the time column and up to three columns to plot, and type their units. Only those columns go on the page; the file stays on this device.

      Two versions' trials your data, compared

      Pick a column of recorded trials for each version, from this page or another saved page. The page shows both averages and a 95% range for the difference. The numbers are copied in when you pick them, so later changes to the other page don't change this one.

      Options compared your scores

      Score each option 1 to 5 on each criterion, and weight each criterion 1 to 5 by how much it matters. The page only multiplies and adds.

      Photos and sketches stay on this device

      Up to 4. Paste a screenshot with Ctrl+V, drop pictures here, or pick them. Photos are shrunk before they’re kept, and an unsaved page keeps them in its draft. Use Mark up to draw arrows, labels, dimensions and numbered callouts on a photo. Mark one photo Before and one After to print them side by side.

        Test plan written before testing

        Write this before you test: the question, what you expect with a number, and what result would make you drop the idea.

          Build steps our build

          One row per step, in order, so someone could rebuild from this page.

            Parts used our parts list

            Lengths in holes are also shown in inches between the end holes. Weights are only added up where you type them.

              Plan the cuts: packs every piece of one part (sizes in holes, or inches on the hole grid) onto whole sticks of the stock length you type.

              Ways it could fail our scores

              List the ways this could fail. Score how likely (1 to 5) and how bad (1 to 5); the page multiplies them and puts the biggest risks first.

                Designed against built our measurements

                What the CAD or the plan said, and what you measured on the robot. The tolerance is yours.

                  Changes from the last version our changes

                  What changed since the last version, why, and which result it was meant to move.

                    That page’s settings, results and first photo are copied in and set beside this page’s. The result each change should move is looked up on both pages.

                    Tasks our plan

                    What needs doing, who, and by when. Open tasks carry to the next meeting page until someone ticks them done.

                      The pages behind this idea our evidence

                      The pages in this notebook that show the idea being tried, measured or changed. A judge reading the claim can turn straight to them.

                        Time spent our hours

                        Who worked on this and for how long.

                          Session log what we did, as we did it

                          Notes taken during a session. The time comes from the clock when the note was taken; every word is yours.

                            Size limit does it fit?

                            Type the starting size limit from the current game manual, and the robot's size as designed or measured, in inches. The site doesn't store the limit, because it changes with the game.

                            What broke from your breakage log

                            The breakage log is on My notebook. Copy it onto this page as a table, as it stands now; later entries don't change this page.

                            CAD model which version this page is about

                            Paste a link to the model (Onshape, Fusion or anything else) and the name you use for this version. For Onshape, the page reads from the link whether it points at a saved version or a workspace that keeps changing. Nothing is fetched.

                            Your code
                            Comments notes for the team, not the page

                            A teammate or coach can leave a note here. Comments stay beside the page, travel with it in exports and links, and don't print unless you tick them under Include.

                              Sources you used besides this tool

                              Videos, other teams, manuals, people. The tool’s own sources are cited for you.

                                Sign-off
                                Include

                                Press a ? to see what an option is for, or read them all on How the notebook tools work.

                                What “The calculator’s figures” is for

                                The calculator’s own diagrams and charts, numbered as figures and drawn from your numbers. Judges look for pictures that explain a design.

                                What “How it was calculated” is for

                                The formulas and steps the calculator used, so a reader can check the arithmetic for themselves.

                                What “The calculator’s warnings” is for

                                Things the calculator flagged, such as a motor near stall. They’re quoted and credited to the calculator, so they never read as your conclusion.

                                What “The calculator’s notes” is for

                                The calculator’s plain-language notes on the result. Off at first, because they read like conclusions, and the conclusions on a page should be yours.

                                What “Lined space” is for

                                Ruled lines under any part you haven’t written yet, so a printed page can be finished by hand.

                                What “Writing space as” is for

                                The blank space for handwriting as ruled lines, a dot grid or quarter-inch squares. Dots and squares suit sketches and hand-drawn graphs.

                                What “A summary under recorded data” is for

                                The number of readings, the average, the spread, the lowest and the highest under each table you recorded, worked out from your numbers. It shows every run counted, not just the best one.

                                What “Words used” is for

                                A small box with the site’s one-line definitions of glossary terms the calculator used, for readers who don’t know them. It never looks at your own writing.

                                What “Robot at the time” is for

                                The Robot Profile as it was when the page was first saved, so weeks later you can tell which version of the robot a test was run on.

                                What “Long tables in full” is for

                                Long calculated tables printed complete on an extra page, instead of every few rows on the page itself.

                                What “Fit on one sheet” is for

                                Smaller type and shorter tables, aiming for one printed sheet. Use it when every entry in your notebook should be a single page.

                                What “Wider left margin” is for

                                A wider left edge, so the page can be hole-punched or bound without losing any words.

                                What “Larger type, for reading aloud” is for

                                Bigger print with more room between lines, for the team member who reads the page to a judge. It overrides Fit on one sheet.

                                What “Our rubric scores” is for

                                Your own scores against the rubric, on a sheet of their own, for checking a page before a judge does.

                                What “When this page was first saved” is for

                                The day the page was first saved, printed beside its date. It shows the notebook was kept while the work happened.

                                What “Teammates’ comments” is for

                                Prints the comments teammates left on this page at the end, marked as not part of the page. Off at first, because comments are notes for the team, not for judges.

                                What “Show every table and block” is for

                                Shows every table and block in the editor, not only the ones this type of page usually uses. It changes the editor, not the printed page.

                                Rubric check

                                  This checks what is on the page, not how good it is. Clear, specific writing in your own words is what earns the top marks.

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                                  Where this goes next

                                  Explore further on the full map

                                  Where the answers on this page can be used, and which tools could have given you the numbers it asks for.

                                  Comes after

                                  Flywheel RPM Drop & Recoverygives you your trial resultsProjectile & Launch Studiogives you your position error

                                  You are here

                                  Shooter Accuracy & Consistency

                                  Where your answer goes

                                  Compare Test Versionsprove a shooter change really raised your hit rate, not just by luckuses your success rate againProjectile & Launch Studiofind the speed or angle change that moves your group onto the targetuses your position error againFlywheel RPM Drop & Recoverysee if uneven flywheel speed between shots is what spreads your groupuses your trial results againMatch Score Modelsee what your shooter is worth in a match once misses are counted

                                  a number carries across the next question it raises

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