Education Technology

Statistics: Effective Blocking
by Texas Instruments


  • Students will be able to identify situations in which blocking will reduce variation.
  • Students will recognize that some randomized block designs are useful in reducing variation while others are not.
  • Students will recognize that random allocation of events occurs within each block.
  • Students will recognize that the experimental units within each block are as similar as possible and different from the experimental units in the other blocks based on a variable that has the potential to affect the outcome of an experiment.


  • experiment
  • experimental units
  • random allocation
  • randomized block design
  • treatments

About the Lesson

This lesson involves investigating the effectiveness of two mosquito sprays in a large tract of land by using three different experimental designs - one randomized design and two randomized block designs.
As a result, students will:

  • Randomly allocate treatments and observe the mean number of mosquitoes in the lots after the sprays have been applied.
  • Compare mean differences and variability for the three experimental designs to determine the most effective design for this context.