Experimental design：练习题

A researcher is designing a study to test the effect of a new fertilizer. They divide a field into 20 plots and use a random number generator to assign 10 plots to receive the fertilizer and 10 plots to act as a control. This is an example of which type of experimental design?

A teacher wishes to compare the effectiveness of two different teaching methods. They select 10 pairs of students, where each pair is matched by their previous exam scores. One student from each pair is randomly assigned to Method A, and the other to Method B. What is the primary benefit of using this blocking (matched pairs) approach?

A study on city noise levels uses a randomised block design. There are 4 different types of sound insulation materials being tested across 5 different types of building structures (the blocks). If the goal is to reduce experimental error, which of the following statements about this design is true?

A medical trial is conducted to test a new drug against a placebo. Neither the patients nor the doctors administering the treatment know which group is receiving the drug and which is receiving the placebo. Explain why this double-blind procedure is used.

In an experimental study comparing two types of soil, a researcher uses blocking to account for the variation in sunlight across the field. Explain the primary benefit of using blocking in this experimental design.

An experiment is designed to compare three different fertilizers using a completely randomised design. Define the role of randomisation in this design and explain how it helps to mitigate experimental error.