Overreaction/original_task.html at main · pennmem/Overreaction · GitHub

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<!doctype html>
<html>
<head>
  <meta charset="utf-8" />
  <title>Forecasting Task</title>
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Source+Serif+4:wght@400;600&display=swap">
  <style>
    body { font-family: "Source Serif 4", system-ui, -apple-system, Segoe UI, Roboto, Arial, serif; max-width: 1000px; margin: 36px auto; padding: 0 16px; }
    .card { border: 1px solid #ddd; border-radius: 14px; padding: 18px 20px; margin: 14px 0; }
    .row { display:flex; gap:14px; flex-wrap:wrap; align-items:flex-end; }
    .row > div { min-width: 220px; }
    label { display:block; margin: 10px 0 6px; }
    input[type="number"]{ width: 200px; padding: 8px; border-radius: 10px; border: 1px solid #ccc; }
    button { padding: 10px 14px; border-radius: 10px; border: 1px solid #ccc; background: #f8f8f8; cursor: pointer; }
    button:disabled { opacity: 0.5; cursor: not-allowed; }
    .muted { color:#666; font-size: 0.95rem; }
    .big { font-size: 1.2rem; }
    #chart, #chart2 { width: 100%; height: 260px; border: 1px solid #eee; border-radius: 12px; }
    .topbar { display:flex; justify-content:space-between; gap: 12px; flex-wrap:wrap; align-items:flex-start; }
    .topbar-right { margin-left:auto; text-align:right; }
    #scroll { width: 100%; margin-top: 6px; }
    code { background:#f2f2f2; padding:2px 6px; border-radius:6px; }
    .debug-meta { display:none; }
  </style>
  <script>
    window.MathJax = {
      tex: { inlineMath: [['$', '$'], ['\\(', '\\)']] },
      svg: { fontCache: 'global' }
    };
  </script>
  <script src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js" async></script>
</head>
<body>
  <h1>Forecasting Task</h1>

  <div id="screen-consent" class="card">
    <p class="big"><b>Consent</b></p>
    <p class="muted">
      You will forecast values of a stable random process across multiple rounds. You will first observe 40 past realizations of the process and then will forecast thereafter.
      Your bonus depends on the accuracy of your forecasts.
    </p>
    <label><input id="consent" type="checkbox"> I consent to participate.</label>
    <button id="btn-begin">Begin</button>
  </div>

  <div id="screen-instructions" class="card" style="display:none;">
    <div class="topbar">
      <div>
        <p class="big"><b>Instructions</b></p>
        <p class="muted">
          You will see a sequence of past values, then complete 40 forecasting rounds.
          In each round you observe the current value $x_t$ and forecast $x_{t+1}$ and $x_{t+2}$.
        </p>
        <p class="muted">
          Your scoring per forecast is $S = 100 \times \max\bigl(0, 1 - \lvert \text{forecast} - \text{realization} \rvert / 20\bigr)$, and your total score is the sum across all forecasts.
          Your score will then be linearly converted to an additional bonus roughly between \$0 and \$5.
        </p>
      </div>
      <div class="debug-meta">
        <p class="muted">Participant ID: <code id="pid"></code></p>
        <p class="muted">Condition (ρ): <code id="rho"></code></p>
      </div>
    </div>

    <p><b>History (40 past realizations)</b></p>
    <canvas id="chart"></canvas>
    <input id="scroll-history" type="range" min="0" max="0" value="0" style="width:100%; margin-top:6px;" />
    <p class="muted">This chart shows the last 40 values of the process. Drag to scroll.</p>

    <button id="btn-start-task">Start forecasting rounds</button>
  </div>

  <div id="screen-task" class="card" style="display:none;">
    <div class="topbar">
      <div>
        <p class="big"><b>Testing phase</b></p>
        <p>Current value: <b id="xt"></b></p>
        <p class="muted">
          Your previous round forecast for $x_{t+2}$ is shown as a grey dot in the $t\!+\!1$ column; you can see it but cannot change it.
        </p>
      </div>
      <div class="topbar-right">
        <p class="big"><b>Score: <span id="score">0</span></b></p>
        <p class="muted"><b>Round <span id="round"></span> of 40</b></p>
      </div>
    </div>

    <canvas id="chart2"></canvas>
    <div>
      <input id="scroll" type="range" min="0" max="0" value="0" />
      <p class="muted">Drag to scroll back and see earlier realizations.</p>
    </div>

    <div class="row">
      <div>
        <label for="f1">Forecast for next period $x_{t+1}$:</label>
        <input id="f1" type="number" step="1" />
      </div>
      <div>
        <label for="f2">Forecast for two periods ahead $x_{t+2}$:</label>
        <input id="f2" type="number" step="1" />
      </div>
      <div>
        <button id="btn-submit">Make prediction</button>
        <p id="err" style="color:#b00; margin:8px 0 0;"></p>
      </div>
    </div>
    <div style="text-align:right; margin-top:4px;" class="muted">
      <span id="latest-scores"></span>
    </div>
  </div>

  <div id="screen-done" class="card" style="display:none;">
    <p class="big"><b>Finished</b></p>
    <p>Your completion code:</p>
    <p class="big"><code id="ccode"></code></p>

    <p class="muted">
      Download your data (JSON) for verification / pilot testing:
    </p>
    <button id="btn-download">Download data</button>

    <p class="muted" style="margin-top:10px;">
      If you want automatic storage, add a server endpoint and POST the <code>payload</code> object.
    </p>
  </div>

<script>
(function () {
  // Parameters
  const MU = 0;
  const SIGMA_E = 20;               // innovation volatility used in scoring denominator
  const RHO_SET = [0.2, 0.6];       // two conditions
  const N_HISTORY = 40;             // shown before task
  const N_ROUNDS = 40;              // forecasting rounds
  // Each round: forecast t+1 and t+2 => 80 scored predictions
  const WINDOW_SIZE = 15;           // visible points in the main chart window

  // Prolific/MTurk URL params if exist
  const qs = new URLSearchParams(window.location.search);
  const prolific_pid = qs.get("PROLIFIC_PID") || "NA";
  const workerId = qs.get("workerId") || "NA";
  const assignmentId = qs.get("assignmentId") || "NA";
  const hitId = qs.get("hitId") || "NA";

  const participant_id = prolific_pid !== "NA" ? prolific_pid : (workerId !== "NA" ? workerId : cryptoRandomId());

  function cryptoRandomId() {
    const a = new Uint32Array(2);
    crypto.getRandomValues(a);
    return "P" + a[0].toString(16) + a[1].toString(16);
  }

  // Randomly assign rho
  const rho = RHO_SET[Math.floor(Math.random() * RHO_SET.length)];
  console.log("Forecasting task participant:", { participant_id, rho });

  // open with ?debug=1 in the URL then shows participant ID and condition
  const isDebug = qs.get("debug") === "1";
  if (isDebug) {
    const metas = document.querySelectorAll(".debug-meta");
    metas.forEach(m => { m.style.display = "block"; });
  }

  // AR(1) generator: x_t = (1-rho)*mu + rho*x_{t-1} + e_t
  function randn() {
    let u = 0, v = 0;
    while (u === 0) u = Math.random();
    while (v === 0) v = Math.random();
    return Math.sqrt(-2.0 * Math.log(u)) * Math.cos(2.0 * Math.PI * v);
  }

  function nextX(prev) {
    const e = SIGMA_E * randn();
    return (1 - rho) * MU + rho * prev + e;
  }

  const totalNeeded = N_HISTORY + N_ROUNDS + 2;
  const x = new Array(totalNeeded);
  x[0] = 0; // initialization
  for (let i = 1; i < totalNeeded; i++) x[i] = nextX(x[i-1]);

  const rawMin = Math.min(...x);
  const rawMax = Math.max(...x);
  const margin = 2 * SIGMA_E;
  const GLOBAL_MIN = rawMin - margin;
  const GLOBAL_MAX = rawMax + margin;

  const t0 = N_HISTORY - 1;

  const trials = [];
  let totalScore = 0;

  let prevF2 = null;

  let currentF1 = null;
  let currentF2 = null;

  let currentRound = 1;
  let viewStart = 0;      // global index of first point in main chart window
  let chartState = null;  // geometry info from last draw
  let dragMode = null;    // whether the user is dragging the t+1 or t+2 forecast

  const lastScores = [];

  // Scoring function
  function scoreOne(forecast, realization) {
    const delta = forecast - realization;
    const s = 100 * Math.max(0, 1 - Math.abs(delta) / SIGMA_E);
    return s;
  }

  function niceInterval(rangeY) {
    const rough = rangeY / 6;
    const magnitude = Math.pow(10, Math.floor(Math.log10(rough)));
    const normalized = rough / magnitude;
    let nice;
    if (normalized < 1.5) nice = 1;
    else if (normalized < 3.5) nice = 2;
    else if (normalized < 7.5) nice = 5;
    else nice = 10;
    return nice * magnitude;
  }

  function drawSeries(canvas, series, opts) {
    const ctx = canvas.getContext("2d");
    const W = canvas.width = canvas.clientWidth * devicePixelRatio;
    const H = canvas.height = canvas.clientHeight * devicePixelRatio;

    ctx.clearRect(0, 0, W, H);

    const pad = 28 * devicePixelRatio;

    const futureSteps = opts && typeof opts.futureSteps === "number" ? opts.futureSteps : 0;

    const fixedMin = opts && typeof opts.fixedMin === "number" ? opts.fixedMin : null;
    const fixedMax = opts && typeof opts.fixedMax === "number" ? opts.fixedMax : null;

    let minY = fixedMin != null ? fixedMin : Math.min(...series);
    let maxY = fixedMax != null ? fixedMax : Math.max(...series);

    // (grey/yellow dots) only if axis is not fixed
    if (!fixedMin || !fixedMax) {
      if (opts) {
        const extraVals = [];
        if (opts.greyDot && typeof opts.greyDot.value === "number") {
          extraVals.push(opts.greyDot.value);
        }
        if (Array.isArray(opts.predictionValues)) {
          for (const v of opts.predictionValues) {
            if (typeof v === "number") extraVals.push(v);
          }
        }
        if (extraVals.length) {
          minY = Math.min(minY, ...extraVals);
          maxY = Math.max(maxY, ...extraVals);
        }
      }
    }

    const rangeY = (maxY - minY) || 1;

    function xPos(i) {
      const denom = (series.length - 1 + futureSteps) || 1;
      return pad + (W - 2*pad) * (i / denom);
    }
    function yPos(v) {
      return H - pad - (H - 2*pad) * ((v - minY) / rangeY);
    }

    // axes
    ctx.strokeStyle = "#e6e6e6";
    ctx.lineWidth = 1 * devicePixelRatio;
    ctx.beginPath();
    ctx.moveTo(pad, pad);
    ctx.lineTo(pad, H - pad);
    ctx.lineTo(W - pad, H - pad);
    ctx.stroke();

    // grid lines
    const interval = niceInterval(rangeY);
    const firstTick = Math.ceil(minY / interval) * interval;
    for (let v = firstTick; v <= maxY; v += interval) {
      const yp = yPos(v);
      const isZero = Math.abs(v) < 1e-9;
      ctx.strokeStyle = isZero ? "#999" : "#eaeaea";
      ctx.lineWidth = isZero ? 1.5 * devicePixelRatio : 1 * devicePixelRatio;
      ctx.setLineDash([]);
      ctx.beginPath();
      ctx.moveTo(pad, yp);
      ctx.lineTo(W - pad, yp);
      ctx.stroke();
    }
    ctx.setLineDash([]);

    // Draw zero line explicitly if in range but missed by tick loop
    if (minY < 0 && maxY > 0 && firstTick > 0) {
      const yp = yPos(0);
      ctx.strokeStyle = "#999";
      ctx.lineWidth = 1.5 * devicePixelRatio;
      ctx.setLineDash([]);
      ctx.beginPath();
      ctx.moveTo(pad, yp);
      ctx.lineTo(W - pad, yp);
      ctx.stroke();
      ctx.setLineDash([]);
    }

    ctx.strokeStyle = "#222";
    ctx.lineWidth = 2 * devicePixelRatio;
    ctx.beginPath();
    for (let i = 0; i < series.length; i++) {
      const xp = xPos(i);
      const yp = yPos(series[i]);
      if (i === 0) ctx.moveTo(xp, yp);
      else ctx.lineTo(xp, yp);
    }
    ctx.stroke();

    // green dots on realizations
    ctx.fillStyle = "#00aa2d";
    for (let i = 0; i < series.length; i++) {
      const xp = xPos(i);
      const yp = yPos(series[i]);
      ctx.beginPath();
      ctx.arc(xp, yp, 4 * devicePixelRatio, 0, 2*Math.PI);
      ctx.fill();
    }

    // numeric labels on realizations
    const showLabels = !opts || opts.showLabels !== false;
    if (showLabels) {
      ctx.fillStyle = "#333";
      ctx.textAlign = "center";
      ctx.textBaseline = "bottom";
      ctx.font = `${10 * devicePixelRatio}px system-ui, -apple-system, Segoe UI`;
      for (let i = 0; i < series.length; i++) {
        const xp = xPos(i);
        const yp = yPos(series[i]);
        ctx.fillText(series[i].toFixed(0), xp, yp - 6 * devicePixelRatio);
      }
    }

    // prediction bands (t+1 in blue, t+2 in red)
    const showBands = !opts || opts.showBands !== false;
    if (showBands) {
      const totalSlots = (series.length - 1 + futureSteps) || 1;
      const innerLeft = pad;
      const innerRight = W - pad;
      const slotWidth = (innerRight - innerLeft) / totalSlots;

      // centers for future slots t+1 and t+2
      const slotIndex1 = series.length;     // first future position
      const slotIndex2 = series.length + 1; // second future position
      const center1 = innerLeft + slotWidth * slotIndex1;
      const center2 = innerLeft + slotWidth * slotIndex2;
      const bandWidth = slotWidth * 0.7;
      const band1Left = center1 - bandWidth / 2;
      const band1Right = center1 + bandWidth / 2;
      const band2Left = center2 - bandWidth / 2;
      const band2Right = center2 + bandWidth / 2;

      ctx.save();
      ctx.globalAlpha = 0.12;
      ctx.fillStyle = "#4a90e2";
      ctx.fillRect(band1Left, pad, bandWidth, H - 2*pad);
      ctx.fillStyle = "#f27b7b";
      ctx.fillRect(band2Left, pad, bandWidth, H - 2*pad);
      ctx.restore();

      ctx.fillStyle = "#333";
      ctx.textAlign = "center";
      ctx.textBaseline = "top";
      ctx.font = `${11 * devicePixelRatio}px system-ui, -apple-system, Segoe UI`;
      ctx.fillText("t+1", (band1Left + band1Right) / 2, pad + 4 * devicePixelRatio);
      ctx.fillText("t+2", (band2Left + band2Right) / 2, pad + 4 * devicePixelRatio);

      // prediction dots if current forecasts exist
      const predictVals = (opts && opts.predictionValues) || [];
      ctx.textAlign = "center";
      ctx.textBaseline = "bottom";
      ctx.font = `${10 * devicePixelRatio}px system-ui, -apple-system, Segoe UI`;

      // grey dot for previous round's t+2 forecast shown in t+1 column (can't be moved, unlabeled)
      const prevBand1Val = opts && typeof opts.previousBand1 === "number" ? opts.previousBand1 : null;
      if (prevBand1Val != null) {
        const yp = yPos(prevBand1Val);
        const cx = (band1Left + band1Right) / 2;
        ctx.fillStyle = "#999999";
        ctx.beginPath();
        ctx.arc(cx, yp, 5 * devicePixelRatio, 0, 2*Math.PI);
        ctx.fill();
      }

      // t+1: yellow dot
      if (predictVals[0] != null) {
        const yp = yPos(predictVals[0]);
        const cx = (band1Left + band1Right) / 2;
        ctx.fillStyle = "#ffcc00";
        ctx.beginPath();
        ctx.arc(cx, yp, 5 * devicePixelRatio, 0, 2*Math.PI);
        ctx.fill();
        ctx.fillStyle = "#333";
        ctx.fillText(predictVals[0].toFixed(0), cx, yp - 7 * devicePixelRatio);
      }

      // t+2: white dot
      if (predictVals[1] != null) {
        const yp = yPos(predictVals[1]);
        const cx = (band2Left + band2Right) / 2;
        ctx.fillStyle = "#ffffff";
        ctx.beginPath();
        ctx.arc(cx, yp, 5 * devicePixelRatio, 0, 2*Math.PI);
        ctx.fill();
        ctx.fillStyle = "#333";
        ctx.textBaseline = "bottom";
        ctx.fillText(predictVals[1].toFixed(0), cx, yp - 7 * devicePixelRatio);
      }

      if (opts && opts.isInteractive) {
        chartState = {
          canvas,
          W,
          H,
          pad,
          minY,
          maxY,
          band1: { x1: band1Left, x2: band1Right },
          band2: { x1: band2Left, x2: band2Right }
        };
      }
    }
  }

  const el = (id) => document.getElementById(id);

  el("pid").textContent = participant_id;
  el("rho").textContent = rho.toString();

  el("btn-begin").onclick = () => {
    if (!el("consent").checked) return alert("Please consent to continue.");
    el("screen-consent").style.display = "none";
    el("screen-instructions").style.display = "block";

    let historyViewStart = Math.max(0, N_HISTORY - WINDOW_SIZE);
    const scrollHistory = el("scroll-history");
    scrollHistory.max = String(historyViewStart);
    scrollHistory.value = String(historyViewStart);

    function renderHistory() {
      const start = Number(scrollHistory.value);
      const shown = x.slice(start, start + WINDOW_SIZE);
      drawSeries(el("chart"), shown, {
        fixedMin: GLOBAL_MIN,
        fixedMax: GLOBAL_MAX,
        showBands: false,
        showLabels: true
      });
}

scrollHistory.addEventListener("input", renderHistory);
renderHistory();
  };

  el("btn-start-task").onclick = () => {
    el("screen-instructions").style.display = "none";
    el("screen-task").style.display = "block";
    renderRound(1);
  };

  function renderRound(r) {
    currentRound = r;
    el("round").textContent = String(r);
    el("score").textContent = totalScore.toFixed(1);

    const t = t0 + r;         // index of current observed value
    const current = x[t];
    el("xt").textContent = current.toFixed(1);

    // reset forecasts for this round
    currentF1 = null;
    currentF2 = null;
    el("f1").value = "";
    el("f2").value = "";
    el("err").textContent = "";

    // scroll range to be able to look back across fixed-size windows
    const maxStart = Math.max(0, t - WINDOW_SIZE + 1);
    const scrollEl = el("scroll");
    scrollEl.max = String(maxStart);
    // by default keep window anchored on the latest point
    scrollEl.value = String(maxStart);
    viewStart = maxStart;

    renderChartForCurrentRound();
  }

  function renderChartForCurrentRound() {
    const t = t0 + currentRound;
    const maxStart = Math.max(0, t - WINDOW_SIZE + 1);
    const start = Math.max(0, Math.min(viewStart, maxStart));
    const end = Math.min(t, start + WINDOW_SIZE - 1);
    const shown = x.slice(start, end + 1);

    const atLatestWindow = (start === maxStart);

    drawSeries(el("chart2"), shown, {
      predictionValues: atLatestWindow ? [currentF1, currentF2] : [],
      fixedMin: GLOBAL_MIN,
      fixedMax: GLOBAL_MAX,
      showBands: atLatestWindow,
      showLabels: true,
      isInteractive: atLatestWindow,
      futureSteps: atLatestWindow ? 2 : 0,
      previousBand1: atLatestWindow ? prevF2 : null
    });
  }

  el("btn-submit").onclick = () => {
    const r = Number(el("round").textContent);
    const f1 = Number(el("f1").value);
    const f2 = Number(el("f2").value);

    if (!Number.isFinite(f1) || !Number.isFinite(f2)) {
      el("err").textContent = "Please enter both forecasts.";
      return;
    }

    currentF1 = f1;
    currentF2 = f2;

    const t = t0 + r;    // observed current index
    const y1 = x[t + 1]; // realization for x_{t+1}
    const y2 = x[t + 2]; // realization for x_{t+2}

    const s1 = scoreOne(f1, y1);
    const s2 = scoreOne(f2, y2);
    totalScore += (s1 + s2);

    lastScores.unshift({ s1, s2 });
    if (lastScores.length > 3) lastScores.pop();
    renderLatestScores();

    trials.push({
      round: r,
      t_index: t,
      x_t: x[t],
      forecast_t1: f1,
      forecast_t2: f2,
      realized_t1: y1,
      realized_t2: y2,
      score_t1: s1,
      score_t2: s2,
      rho,
      mu: MU,
      sigma_e: SIGMA_E,
      timestamp: new Date().toISOString()
    });

    prevF2 = f2;

    if (r < N_ROUNDS) {
      renderRound(r + 1);
    } else {
      finish();
    }
  };

  function renderLatestScores() {
    const elLS = el("latest-scores");
    if (!elLS) return;
    if (!lastScores.length) {
      elLS.textContent = "";
      return;
    }
    const parts = lastScores.map(pair => {
      const s1 = Math.round(pair.s1);
      const s2 = Math.round(pair.s2);
      const fmt1 = (s1 >= 0 ? "+" : "") + s1;
      const fmt2 = (s2 >= 0 ? "+" : "") + s2;
      return `(<span style="color:#1f77b4">${fmt1}</span>, <span style="color:#d62728">${fmt2}</span>)`;
    });
    elLS.innerHTML = parts.join(" ") + ' | Latest scores';
  }

  el("f1").addEventListener("input", () => {
    const v = Number(el("f1").value);
    currentF1 = Number.isFinite(v) ? v : null;
    renderChartForCurrentRound();
  });
  el("f2").addEventListener("input", () => {
    const v = Number(el("f2").value);
    currentF2 = Number.isFinite(v) ? v : null;
    renderChartForCurrentRound();
  });

  el("scroll").addEventListener("input", () => {
    viewStart = Number(el("scroll").value);
    renderChartForCurrentRound();
  });

  function yToValue(yDevicePx) {
    if (!chartState) return null;
    const { H, pad, minY, maxY } = chartState;
    const usableH = H - 2 * pad;
    const clampedY = Math.max(pad, Math.min(H - pad, yDevicePx));
    const frac = (H - pad - clampedY) / usableH;
    return minY + frac * (maxY - minY);
  }

  function handleDragUpdate(which, clientX, clientY) {
    if (!chartState) return;
    const { canvas, band1, band2 } = chartState;
    const rect = canvas.getBoundingClientRect();
    const x = (clientX - rect.left) * devicePixelRatio;
    const y = (clientY - rect.top) * devicePixelRatio;

    const band = which === "f1" ? band1 : band2;
    if (!band || x < band.x1 || x > band.x2) return;
    const val = yToValue(y);
    if (val == null) return;

    if (which === "f1") {
      currentF1 = val;
      el("f1").value = val.toFixed(0);
    } else {
      currentF2 = val;
      el("f2").value = val.toFixed(0);
    }
    renderChartForCurrentRound();
  }

  (function attachCanvasHandlers() {
    const canvas = el("chart2");
    canvas.addEventListener("mousedown", (ev) => {
      if (!chartState) return;
      const rect = canvas.getBoundingClientRect();
      const x = (ev.clientX - rect.left) * devicePixelRatio;
      const { band1, band2 } = chartState;
      if (band1 && x >= band1.x1 && x <= band1.x2) {
        dragMode = "f1";
      } else if (band2 && x >= band2.x1 && x <= band2.x2) {
        dragMode = "f2";
      } else {
        dragMode = null;
      }
      if (dragMode) {
        handleDragUpdate(dragMode, ev.clientX, ev.clientY);
      }
    });

    window.addEventListener("mousemove", (ev) => {
      if (!dragMode) return;
      handleDragUpdate(dragMode, ev.clientX, ev.clientY);
    });

    window.addEventListener("mouseup", () => {
      dragMode = null;
    });

    canvas.addEventListener("mouseleave", () => {
      dragMode = null;
    });
  })();

  function finish() {
    el("screen-task").style.display = "none";
    el("screen-done").style.display = "block";

    const payload = {
      participant_id,
      prolific_pid,
      workerId,
      assignmentId,
      hitId,
      condition_rho: rho,
      mu: MU,
      sigma_e: SIGMA_E,
      n_history: N_HISTORY,
      n_rounds: N_ROUNDS,
      total_score: totalScore,
      implied_bonus_mturk_paper: totalScore / 600,
      trials
    };

    const ccode = makeCompletionCode(payload);
    el("ccode").textContent = ccode;

    el("btn-download").onclick = () => {
      const blob = new Blob([JSON.stringify({ ...payload, completion_code: ccode }, null, 2)], { type: "application/json" });
      const a = document.createElement("a");
      a.href = URL.createObjectURL(blob);
      a.download = `forecast_task_${participant_id}.json`;
      a.click();
    };
  }

  function makeCompletionCode(payload) {
    const base = `${payload.participant_id}|${payload.condition_rho}|${payload.total_score.toFixed(2)}|${Date.now()}`;
    let h = 2166136261;
    for (let i = 0; i < base.length; i++) {
      h ^= base.charCodeAt(i);
      h = Math.imul(h, 16777619);
    }
    return "CC" + (h >>> 0).toString(16).toUpperCase().padStart(8, "0");
  }
})();
</script>
</body>
</html>