Measurement Methodology & Technical Specifications

Specification Metric Version v2.0 • Transparent Mathematical Formulas

1. Monotonic High-Resolution Timing

All event intervals and session durations are measured via the browser’s standard performance.now() API rather than wall-clock Date.now(). The monotonic clock guarantees that time measurements never jump backward due to system clock synchronization (NTP) or daylight saving adjustments, achieving microsecond-level relative precision.

2. Mouse Polling Rate & Interval Jitter Mathematics

Mouse polling rate frequency (Hz) is calculated over sliding windows and session totals:

Average Hz = Total Valid Events / Elapsed Monotonic Seconds

Interval Jitter ($\sigma$) represents the standard deviation of inter-event spacing across $N$ recorded updates:

$\sigma = \sqrt{\frac{1}{N}\sum_{i=1}^N (\Delta t_i - \mu)^2}$

3. Strict Delta Mode Unit Isolation

The W3C DOM Level 3 Events specification defines three distinct delta modes for wheel events:

DOM_DELTA_PIXEL (0): Movement expressed in CSS pixels (typical of precision touchpads).
DOM_DELTA_LINE (1): Movement expressed in physical text lines (typical of detented mouse wheels).
DOM_DELTA_PAGE (2): Movement expressed in full viewport page increments.

MouseTesterPro.online never merges pixel, line, and page values into a single misleading composite sum. Each delta unit is accumulated and reported in its genuine native scale.

4. Centralized Diagnostic Thresholds

Parameter	Configured Value	Mathematical Criterion
Irregular Gap	> 250 ms	Consecutive event interval exceeding 250 milliseconds during active scroll
Burst Delivery	≤ 8 ms (≥ 3 events)	Groups of 3 or more events separated by 8ms or less
Sufficient Sample	≥ 3 events	Minimum expected directional events for a phase to be conclusive
Repeatability Protocol	≥ 3 runs	Strict multi-run comparison requiring identical duration, device, and profile

What Browser Tests Cannot Prove

A browser-based test cannot conclusively confirm physical hardware component failure. Software factors like operating system background scheduling, browser window throttling, USB controller power management, and browser extensions can introduce timing gaps or dropped frames. MouseTesterPro.online always uses neutral diagnosis descriptions like "Pattern worth retesting" or "No suspicious pattern observed" rather than making speculative hardware failure claims.