Table 6

Comparison of observed average total time on task (TOT, min) with that predicted under length biased sampling and no additional penalty due to interruptions

Observation sessionsAverage interruption rate per hourNo of interruptionsSample size (n)Average TOT (min) predicted under length-biased sampling (A)Observed average TOT (min) (B)Percentage observed mean to predicted (B/A%)Z*
1 to 1515.411454.502.0245–5.0
16 to 667.712635.003.3367–4.8
67 to 1313.312045.883.2856–5.3
  • * All test statistics reject the null hypothesis of no impact due to interruptions with p-values less than 0.0005 in all cases. The negative Z values indicate that the observed TOTs for interrupted tasks were significantly lower than expected.

  • The predicted average TOT for three or more interruptions is calculated using the formula for three interruptions.