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Introduction

Assume we are dealing with an observation, in time, of a sample of "n" entities placed on test (be these, devices or humans). The experimental observation period is defined as the time elapsed since the experiment begins (time zero) until it is terminated (time T0). However, it often occurs that we need to discontinue our experiment before all the elements in the sample experience the "event of interest" (e.g., failure or death). In such cases, we say that the experiment has been "suspended," "censored," or "truncated".

"Truncation" may not be the most efficient way to conduct an experiment, from the theoretical standpoint. But, due to time, economic or practical considerations, it happens so frequently that statistics had to find ways to deal with it in a successful manner. In this START sheet we overview some of these statistical procedures, we illustrate them via several practical, numerical examples and we provide some references for further reading.