Add standard deviation display for predicted ratings

- Calculate and store standard deviation during rating prediction
- Add std_dev column to players database table
- Display standard deviation tooltip on hover over predicted rating
- Show rating range (±std_dev) tooltip on hover over current rating
- Update tooltips dynamically when ratings are refreshed

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

index.html

@@ -196,6 +196,25 @@
             font-weight: bold;
             color: #007bff;
         }
+        .std-dev-tooltip {
+            position: absolute;
+            background-color: rgba(0, 0, 0, 0.9);
+            color: white;
+            padding: 8px 12px;
+            border-radius: 4px;
+            font-size: 12px;
+            pointer-events: none;
+            z-index: 10000;
+            display: none;
+            white-space: nowrap;
+            box-shadow: 0 2px 8px rgba(0,0,0,0.3);
+            border: 1px solid rgba(255,255,255,0.2);
+            font-weight: normal;
+        }
+        .predicted-value {
+            position: relative;
+            display: inline-block;
+        }
         .pdga-number {
             color: #6c757d;
             font-size: 14px;
@@ -582,18 +601,20 @@
                         <td class="pdga-number mobile-hide">#${player.pdgaNumber}</td>
                         <td class="rating">
                             <div class="refresh-section">
-                                ${player.rating || '<span style="color: #999; font-style: italic;">Click refresh</span>'}
+                                <span class="rating-value" data-rating="${player.rating || ''}" data-stddev="${player.stdDev || ''}" data-pdga="${player.pdgaNumber}" style="cursor: help;">${player.rating || '<span style="color: #999; font-style: italic;">Click refresh</span>'}</span>
                                 <i class="fas fa-sync-alt refresh-icon" onclick="refreshPlayer(${player.pdgaNumber})" title="Refresh player data"></i>
                             </div>
                             <div class="mobile-only rating-change ${ratingChangeClass}" style="font-size: 11px; margin-top: 2px;">${ratingChangeText}</div>
+                            <div class="std-dev-tooltip" id="tooltip-rating-${player.pdgaNumber}"></div>
                         </td>
                         <td class="rating-change ${ratingChangeClass} mobile-hide">${ratingChangeText}</td>
                         <td class="predicted-rating mobile-hide" id="predicted-${player.pdgaNumber}">
                             <div class="refresh-section">
-                                ${player.predictedRating || 'N/A'}
+                                <span class="predicted-value" data-stddev="${player.stdDev || ''}" data-pdga="${player.pdgaNumber}" style="cursor: help;">${player.predictedRating || 'N/A'}</span>
                                 <i class="fas fa-question-circle debug-icon" onclick="showDebugInfo(${player.pdgaNumber})" title="Show calculation details" style="margin-left: 5px; color: #6c757d; cursor: pointer; opacity: 0.6;"></i>
                                 <i class="fas fa-sync-alt refresh-icon" onclick="refreshRoundHistory(${player.pdgaNumber})" title="Refresh prediction data"></i>
                             </div>
+                            <div class="std-dev-tooltip" id="tooltip-stddev-${player.pdgaNumber}"></div>
                         </td>
                     </tr>
                     <tr id="history-${player.pdgaNumber}" class="expanded-content">
@@ -619,6 +640,60 @@
             `;
             
             tableDiv.innerHTML = tableHTML;
+
+            // Add hover listeners for predicted rating standard deviation tooltips
+            document.querySelectorAll('.predicted-value').forEach(span => {
+                const pdgaNumber = span.dataset.pdga;
+                const stdDev = span.dataset.stddev;
+                const tooltip = document.getElementById(`tooltip-stddev-${pdgaNumber}`);
+
+                if (stdDev && tooltip) {
+                    span.addEventListener('mouseenter', (e) => {
+                        tooltip.textContent = `Standard Deviation: ±${stdDev}`;
+                        tooltip.style.display = 'block';
+                        tooltip.style.left = `${e.clientX + 15}px`;
+                        tooltip.style.top = `${e.clientY - 35}px`;
+                    });
+
+                    span.addEventListener('mousemove', (e) => {
+                        tooltip.style.left = `${e.clientX + 15}px`;
+                        tooltip.style.top = `${e.clientY - 35}px`;
+                    });
+
+                    span.addEventListener('mouseleave', () => {
+                        tooltip.style.display = 'none';
+                    });
+                }
+            });
+
+            // Add hover listeners for current rating range tooltips
+            document.querySelectorAll('.rating-value').forEach(span => {
+                const pdgaNumber = span.dataset.pdga;
+                const rating = parseInt(span.dataset.rating);
+                const stdDev = parseInt(span.dataset.stddev);
+                const tooltip = document.getElementById(`tooltip-rating-${pdgaNumber}`);
+
+                if (rating && stdDev && tooltip) {
+                    const minRating = rating - stdDev;
+                    const maxRating = rating + stdDev;
+
+                    span.addEventListener('mouseenter', (e) => {
+                        tooltip.textContent = `Rating Range: ${minRating} - ${maxRating} (±${stdDev})`;
+                        tooltip.style.display = 'block';
+                        tooltip.style.left = `${e.clientX + 15}px`;
+                        tooltip.style.top = `${e.clientY - 35}px`;
+                    });
+
+                    span.addEventListener('mousemove', (e) => {
+                        tooltip.style.left = `${e.clientX + 15}px`;
+                        tooltip.style.top = `${e.clientY - 35}px`;
+                    });
+
+                    span.addEventListener('mouseleave', () => {
+                        tooltip.style.display = 'none';
+                    });
+                }
+            });
         }
 
 
@@ -846,8 +921,45 @@
                     const ratingChangeClass = data.player.ratingChange > 0 ? 'positive' : 
                                             data.player.ratingChange < 0 ? 'negative' : 'neutral';
                     
-                    const refreshSection = ratingCell.querySelector('.refresh-section');
+                    // Update rating value
-                    refreshSection.innerHTML = `${data.player.rating || 'N/A'} <i class="fas fa-sync-alt refresh-icon" onclick="refreshPlayer(${pdgaNumber})" title="Refresh player data"></i>`;
+                    const ratingValue = ratingCell.querySelector('.rating-value');
+                    if (ratingValue) {
+                        ratingValue.textContent = data.player.rating || 'N/A';
+                        ratingValue.dataset.rating = data.player.rating || '';
+                        // stdDev stays the same - only updates with predicted rating refresh
+
+                        // Re-attach tooltip listeners if we have both rating and stdDev
+                        const stdDev = parseInt(ratingValue.dataset.stddev);
+                        const rating = parseInt(data.player.rating);
+                        const tooltip = document.getElementById(`tooltip-rating-${pdgaNumber}`);
+
+                        if (rating && stdDev && tooltip) {
+                            // Remove old listeners by cloning and replacing
+                            const newRatingValue = ratingValue.cloneNode(true);
+                            ratingValue.parentNode.replaceChild(newRatingValue, ratingValue);
+
+                            const minRating = rating - stdDev;
+                            const maxRating = rating + stdDev;
+
+                            // Add new listeners
+                            newRatingValue.addEventListener('mouseenter', (e) => {
+                                tooltip.textContent = `Rating Range: ${minRating} - ${maxRating} (±${stdDev})`;
+                                tooltip.style.display = 'block';
+                                tooltip.style.left = `${e.clientX + 15}px`;
+                                tooltip.style.top = `${e.clientY - 35}px`;
+                            });
+
+                            newRatingValue.addEventListener('mousemove', (e) => {
+                                tooltip.style.left = `${e.clientX + 15}px`;
+                                tooltip.style.top = `${e.clientY - 35}px`;
+                            });
+
+                            newRatingValue.addEventListener('mouseleave', () => {
+                                tooltip.style.display = 'none';
+                            });
+                        }
+                    }
+
                     if (ratingChangeCell) ratingChangeCell.textContent = ratingChangeText;
                     if (ratingChangeCell) ratingChangeCell.className = `rating-change ${ratingChangeClass} mobile-hide`;
 
@@ -891,9 +1003,75 @@
                     // Update predicted rating if the element exists
                     const predictedCell = document.getElementById(`predicted-${pdgaNumber}`);
                     if (predictedCell) {
-                        const refreshSection = predictedCell.querySelector('.refresh-section');
+                        const predictedValue = predictedCell.querySelector('.predicted-value');
-                        if (refreshSection && refreshSection.firstChild) {
+                        if (predictedValue) {
-                            refreshSection.firstChild.textContent = data.predictedRating || 'N/A';
+                            predictedValue.textContent = data.predictedRating || 'N/A';
+                            // Update data attribute for tooltip
+                            predictedValue.dataset.stddev = data.stdDev || '';
+
+                            // Re-attach tooltip listeners
+                            const tooltip = document.getElementById(`tooltip-stddev-${pdgaNumber}`);
+                            if (data.stdDev && tooltip) {
+                                // Remove old listeners by cloning and replacing
+                                const newPredictedValue = predictedValue.cloneNode(true);
+                                predictedValue.parentNode.replaceChild(newPredictedValue, predictedValue);
+
+                                // Add new listeners
+                                newPredictedValue.addEventListener('mouseenter', (e) => {
+                                    tooltip.textContent = `Standard Deviation: ±${data.stdDev}`;
+                                    tooltip.style.display = 'block';
+                                    tooltip.style.left = `${e.clientX + 15}px`;
+                                    tooltip.style.top = `${e.clientY - 35}px`;
+                                });
+
+                                newPredictedValue.addEventListener('mousemove', (e) => {
+                                    tooltip.style.left = `${e.clientX + 15}px`;
+                                    tooltip.style.top = `${e.clientY - 35}px`;
+                                });
+
+                                newPredictedValue.addEventListener('mouseleave', () => {
+                                    tooltip.style.display = 'none';
+                                });
+                            }
+                        }
+                    }
+
+                    // Also update the rating value's stddev attribute and tooltip
+                    const row = document.getElementById(`row-${pdgaNumber}`);
+                    const ratingCell = row.querySelector('.rating');
+                    const ratingValue = ratingCell.querySelector('.rating-value');
+                    if (ratingValue && data.stdDev) {
+                        ratingValue.dataset.stddev = data.stdDev;
+
+                        // Re-attach rating tooltip listeners if we have both rating and stdDev
+                        const rating = parseInt(ratingValue.dataset.rating);
+                        const stdDev = parseInt(data.stdDev);
+                        const ratingTooltip = document.getElementById(`tooltip-rating-${pdgaNumber}`);
+
+                        if (rating && stdDev && ratingTooltip) {
+                            // Remove old listeners by cloning and replacing
+                            const newRatingValue = ratingValue.cloneNode(true);
+                            ratingValue.parentNode.replaceChild(newRatingValue, ratingValue);
+
+                            const minRating = rating - stdDev;
+                            const maxRating = rating + stdDev;
+
+                            // Add new listeners
+                            newRatingValue.addEventListener('mouseenter', (e) => {
+                                ratingTooltip.textContent = `Rating Range: ${minRating} - ${maxRating} (±${stdDev})`;
+                                ratingTooltip.style.display = 'block';
+                                ratingTooltip.style.left = `${e.clientX + 15}px`;
+                                ratingTooltip.style.top = `${e.clientY - 35}px`;
+                            });
+
+                            newRatingValue.addEventListener('mousemove', (e) => {
+                                ratingTooltip.style.left = `${e.clientX + 15}px`;
+                                ratingTooltip.style.top = `${e.clientY - 35}px`;
+                            });
+
+                            newRatingValue.addEventListener('mouseleave', () => {
+                                ratingTooltip.style.display = 'none';
+                            });
                         }
                     }
                     

server.js

@@ -54,6 +54,7 @@ function initializeDatabase() {
 
           const hasLastRoundUpdate = columns.some(col => col.name === 'last_round_update');
           const hasPredictedRating = columns.some(col => col.name === 'predicted_rating');
+          const hasStdDev = columns.some(col => col.name === 'std_dev');
 
           if (!hasLastRoundUpdate) {
             console.log('Adding last_round_update column to players table...');
@@ -80,6 +81,19 @@ function initializeDatabase() {
               }
             });
           }
+
+          if (!hasStdDev) {
+            console.log('Adding std_dev column to players table...');
+            db.run(`
+              ALTER TABLE players ADD COLUMN std_dev INTEGER DEFAULT NULL
+            `, (err) => {
+              if (err) {
+                console.error('Error adding std_dev column:', err.message);
+              } else {
+                console.log('Successfully added std_dev column');
+              }
+            });
+          }
         });
       });
 
@@ -533,8 +547,12 @@ async function getPlayerDataFromDB(pdgaNumber) {
 
       // Use stored predicted_rating if available, otherwise calculate it from round history
       let predictedRating = cachedPlayer.predicted_rating;
+      let stdDev = cachedPlayer.std_dev;
       if (!predictedRating || predictedRating === 0) {
         predictedRating = await getPredictedRatingFromDB(pdgaNumber);
+        // After calculation, re-fetch to get the updated std_dev
+        const updatedPlayer = await getPlayerFromDB(pdgaNumber);
+        stdDev = updatedPlayer?.std_dev;
       }
 
       return {
@@ -542,7 +560,8 @@ async function getPlayerDataFromDB(pdgaNumber) {
         name: cachedPlayer.name,
         rating: cachedPlayer.current_rating,
         ratingChange: cachedPlayer.rating_change,
-        predictedRating: predictedRating > 0 ? predictedRating : null
+        predictedRating: predictedRating > 0 ? predictedRating : null,
+        stdDev: stdDev > 0 ? stdDev : null
       };
     }
     return null; // No data in DB
@@ -653,7 +672,7 @@ async function getPredictedRatingFromDB(pdgaNumber) {
       const result = calculatePredictedRating(roundRatings);
 
       // Save the calculated prediction to database
-      await savePredictedRatingToDB(pdgaNumber, result.rating);
+      await savePredictedRatingToDB(pdgaNumber, result.rating, result.stdDev);
 
       return result.rating;
     }
@@ -664,11 +683,11 @@ async function getPredictedRatingFromDB(pdgaNumber) {
   }
 }
 
-function savePredictedRatingToDB(pdgaNumber, predictedRating) {
+function savePredictedRatingToDB(pdgaNumber, predictedRating, stdDev = null) {
   return new Promise((resolve, reject) => {
     db.run(
-      'UPDATE players SET predicted_rating = ? WHERE pdga_number = ?',
+      'UPDATE players SET predicted_rating = ?, std_dev = ? WHERE pdga_number = ?',
-      [predictedRating, pdgaNumber],
+      [predictedRating, stdDev, pdgaNumber],
       function(err) {
         if (err) reject(err);
         else resolve();
@@ -1484,14 +1503,18 @@ function calculatePredictedRating(roundRatings) {
   const average = sum / weightedRatings.length;
   const finalRating = Math.round(average);
 
+  // Calculate standard deviation of the weighted ratings
+  const stdDev = calculateStandardDeviation(weightedRatings);
+
   debugLog.push('🎯 FINAL CALCULATION:');
   debugLog.push(`   Sum: ${sum}`);
   debugLog.push(`   Count: ${weightedRatings.length}`);
   debugLog.push(`   Average: ${average.toFixed(1)}`);
+  debugLog.push(`   Standard Deviation: ${stdDev.toFixed(1)}`);
   debugLog.push(`   Final Rating: ${finalRating}`);
   debugLog.push('=== END PDGA CALCULATION ===');
 
-  return { rating: finalRating, debugLog };
+  return { rating: finalRating, stdDev: Math.round(stdDev), debugLog };
 }
 
 function calculateStandardDeviation(ratings) {
@@ -2773,7 +2796,7 @@ app.post('/api/refresh-round-history/:pdgaNumber', async (req, res) => {
     const result = calculatePredictedRating(roundsForPrediction);
 
     // Save the predicted rating to database for persistence
-    await savePredictedRatingToDB(pdgaNumber, result.rating);
+    await savePredictedRatingToDB(pdgaNumber, result.rating, result.stdDev);
 
     // Count official vs new rounds
     const officialCount = allRounds.filter(r => r.source === 'official').length;
@@ -2782,6 +2805,7 @@ app.post('/api/refresh-round-history/:pdgaNumber', async (req, res) => {
     res.json({
       success: true,
       predictedRating: result.rating,
+      stdDev: result.stdDev,
       debugLog: result.debugLog,
       totalRounds: roundsForPrediction.length,
       officialRounds: officialCount,
@@ -3323,6 +3347,7 @@ app.post('/api/predicted-rating/:pdgaNumber', async (req, res) => {
     res.json({
       pdgaNumber: parseInt(pdgaNumber),
       predictedRating: result.rating,
+      stdDev: result.stdDev,
       debugLog: result.debugLog
     });
   } catch (error) {