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Rating deltas is one of the 28 app marketplace metrics and concepts defined in the AppRanks glossary. This page gives you a clear, plain-language explanation of what Rating deltas means, why it matters when you evaluate an app, how AppRanks calculates and verifies it, and exactly where you will see it across our public app, audit, and comparison pages. Read on for the full definition, practical use cases, and links to related terms so you can interpret Rating deltas with confidence.
Also known as: rating change, rating trend, rating drift
The signed change in an app's average rating across rolling time windows — typically 7-day, 30-day, and 90-day deltas. A rating delta of +0.03 over 7 days means the average climbed from (e.g.) 4.62 → 4.65; a delta of -0.10 means it dropped. Small numbers carry large information because a marketplace listing with 500+ reviews moves slowly under random noise: a 0.05-point drop in 7 days usually represents 20-50 negative reviews landing in concentrated time, not statistical drift — a signal worth investigating BEFORE the headline rating crosses a visible threshold or the marketplace's algorithm reweights the listing. AppRanks shows the per-window delta alongside the absolute rating on every app page so a stable 4.6 with a -0.08 v7d gets flagged differently than a stable 4.6 with a +0.02 v7d. The delta column is also where most early-warning signals first surface — a soft launch failing to convert, a competitor pulling installs away, or a quality regression triggering negative feedback.
Rating deltas are the earliest visible trouble signal on an established listing. By the time the absolute rating crosses below 4.5 — a common review-quality threshold for marketplaces — the underlying delta has typically been negative for weeks. Watching the delta lets a developer respond inside the window where corrective action (responding to recent 1-star reviews, shipping a hotfix, updating the listing FAQ) can still move the trajectory back. For competitive intelligence, a competitor's rating-delta turning negative two cycles in a row is often the leading indicator of an install-velocity reversal.
AppRanks computes rating deltas by snapshotting the rolling-window average rating at every scrape and diffing across the requested window (7/30/90 days). We do not annualize partial windows for apps newer than the window length — instead the delta is computed against whatever portion of the window has data, and the partial-window flag is surfaced on the timeline. Deltas are sign-preserving and rounded to two decimals.