Creative Fatigue

CPI stands for Cost Per Install, meaning the cost that an advertiser pays each time a user installs their mobile app after clicking on an ad. CPI is a performance-based pricing model, which means that the advertiser only pays for results that directly contribute to their business goals, such as app installations. This pricing model is particularly popular among mobile app developers who want to promote their apps and acquire new users.

Impression-to-install rate (also called IPM — Installs Per Mille, or installs per thousand impressions) measures the percentage of ad impressions that ultimately result in an app install. It is calculated by dividing the number of installs by the number of ad impressions and multiplying by 100 (or by 1,000 for the IPM variant). This metric combines ad engagement efficiency (do people click?) with post-click conversion efficiency (do people install after clicking?), making it a holistic measure of creative and targeting quality. A high impression-to-install rate indicates that the ad creative resonates with the target audience and that the app store listing or landing page effectively converts interested users. Typical impression-to-install rates vary significantly by ad format and vertical, with video ads and rewarded formats generally outperforming static banners. Monitoring this rate across different creatives, audiences, and placements helps growth teams identify their most efficient combinations and detect creative fatigue early.

A/B testing (also called split testing) is a method of comparing two or more variations of a product experience — such as a paywall design, landing page layout, pricing structure, or onboarding flow — to determine which version performs better against a defined metric. In mobile app monetization, A/B testing is used extensively to optimize conversion rates, trial starts, subscription sign-ups, and revenue per user. Traffic is randomly split between variants, and statistical analysis determines whether differences in performance are meaningful or due to chance. Effective A/B testing requires a clear hypothesis, a single variable change per test, sufficient sample size, and patience to reach statistical significance before drawing conclusions.

User acquisition refers to the strategies and activities used to attract new users to a mobile app or platform. It encompasses paid advertising, organic discovery, and referral programs working together to drive installs and grow an engaged user base.

Cost Per Mille (CPM), also known as cost per thousand impressions, is an advertising pricing model where advertisers pay a fixed rate for every 1,000 times their ad is displayed to users. "Mille" is Latin for thousand. CPM is one of the most common buying models in digital advertising, particularly for brand awareness campaigns and display advertising. In the mobile app ecosystem, CPM is used both by app developers buying ads to acquire users and by app publishers selling ad inventory within their apps. For user acquisition, CPM campaigns are typically less performance-oriented than CPI or CPA models, since the advertiser pays for visibility rather than a specific action. However, CPM can be effective for reaching large audiences at scale and building brand recognition. For app publishers monetizing with ads, CPM represents the revenue earned per 1,000 ad impressions served — also called eCPM (effective CPM) — and is a core metric for evaluating ad monetization performance across different ad networks and formats.