Opinium achieved a PolitPro Score of 71 out of 100.
On average, Opinium's figures deviate by 1.7 percentage points between their final pre-election polls and actual election results.
In 42% of polls, Opinium rated Labour higher than the PolitPro Election Trend (average of all institutes).
In 44% of polls, Opinium rated Reform UK higher than the PolitPro Election Trend (average of all institutes).
In 25% of polls, Opinium rated Tories higher than the PolitPro Election Trend (average of all institutes).
In 35% of polls, Opinium rated Labour lower than the PolitPro Election Trend (average of all institutes).
In 36% of polls, Opinium rated Liberal Democrats lower than the PolitPro Election Trend (average of all institutes).
In 30% of polls, Opinium rated Tories lower than the PolitPro Election Trend (average of all institutes).
The PolitPro Election Trend serves as the benchmark, using a time-weighted average of all current surveys. A poll value is flagged if it deviates by more than one percentage point from this trend.
On average, Opinium's figures deviate by 1.7 percentage points between their final pre-election polls and actual election results.
With an average deviation of 2.78 percentage points per party, Opinium ranks 3 out of 9.
With an average deviation of 0.70 percentage points per party, Opinium ranks 4 out of 12.
Accuracy indicates how closely pre-election polls aligned with actual election results. We compare final surveys from various institutes with official outcomes. To do this, we calculate the average deviation across all parties that received at least 3% of the vote. Most election polls have a standard margin of error of 2-3 percentage points. We categorize average deviations as follows: up to 1 percentage point is "very good" (green); up to 2 points is "good" (yellow); up to 3 points is "acceptable" (orange), though this may indicate significant outliers for specific parties. Deviations exceeding 3 percentage points suggest a lack of predictive power and are rated "poor" (red).