Crowdtesting has grown to be an effective alternative to traditional testing, especially in mobile apps. However, crowdtesting is hard to manage in nature. Given the complexity of mobile applications and unpredictability of distributed, parallel crowdtesting process, it is difficult to estimate (a) the remaining number of bugs as yet undetected or (b) the required cost to find those bugs. Experience-based decisions may result in ineffective crowdtesting process.This paper aims at exploring automated decision support to effectively manage crowdtesting process. The proposed ISENSE applies incremental sampling technique to process crowdtesting reports arriving in chronological order, organizes them into fixedsize groups as dynamic inputs, and predicts two test completion indicators in an incrementally manner. The two indicators are: 1) total number of bugs predicted with Capture-ReCapture (CRC) model, and 2) required test cost for achieving certain test objectives predicted with AutoRegressive Integrated Moving Average (ARIMA) model. We assess ISENSE using 46,434 reports of 218 crowdtesting tasks from one of the largest crowdtesting platforms in China. Its effectiveness is demonstrated through two applications for automating crowdtesting management, i.e. automation of task closing decision, and semi-automation of task closing tradeoff analysis. The results show that decision automation using ISENSE will provide managers with greater opportunities to achieve cost-effectiveness gains of crowdtesting. Specifically, a median of 100% bugs can be detected with 30% saved cost based on the automated close prediction.1 ISENSE is named considering it likes a sensor in crowdtesting process to raise the awareness of the testing progress.