The text explicitly states what type of measurement tends to overestimate partial interval Partial interval recording tends to overestimate the duration or frequency of behavior because a response is recorded if it occurs at any point during the interval even if it is very brief eg 1 second in a 10second interval When subsequently reported as a percentage of intervals it gives the impression that the behavior occurred throughout the entire interval leading to an inflated representation of the behaviors true occurrence or duration For instance if handflapping occurs for only 1 second in each of 10 intervals partial interval recording would show 100 occurrence when the actual duration was only 10 seconds In contrast whole interval recording option A tends to underestimate behavior because it only records an occurrence if the behavior occurs throughout the entire interval Momentary time sampling option C can either over or underestimate depending on the behaviors pattern and interval length Event recording option D is a continuous measurement and when implemented correctly provides an accurate frequency count without inherent overunderestimation biases in the same way discontinuous methods do