Question

question #8
an experiment will be conducted to determine whether children learn their multiplication facts better by practicing with flash cards or by practicing on a computer. children who volunteer for the experiment will be randomly assigned to one of the two treatments. because the childrens gender may affect the outcome, there will be blocking by gender. after practice, the children will be given a test on their multiplication facts.
which element of experimental design is known to be a part of this study?
matched pairs design
double blind
blocking design
randomized comparative design
question #9
consider an experiment to investigate the effectiveness of different insecticides in controlling pests and their impact on tomato plants. what is the best reason for randomly assigning treatment levels (spraying or not spraying) to the experimental units (farms)?
randomization makes the analysis easier since the data can be collected and entered into the computer in any order.
randomization is a good way to create two groups of farms that are as similar as possible, so that comparisons can be made between the two groups.
randomization eliminates the impact of any confounding variables.
randomization ensures that the study is double blind.

Explanation:

Question #8

• Matched Pairs Design: Involves pairing subjects and assigning each to different treatments. Not mentioned here.
• Double Blind: Neither subjects nor experimenters know treatment assignments. Not indicated.
• Blocking Design: Grouping (blocking) by a variable (gender here) to reduce variability. Explicitly stated.
• Randomized Comparative Design: Just random assignment to treatments. But blocking is a more specific fit as it's mentioned.

• Randomization makes analysis easier: Not the core reason. The goal is valid comparison.
• Create similar groups: Random assignment helps balance out confounding variables (like soil quality, sunlight on farms) so groups are comparable.
• Eliminates impact of confounding variables: "Eliminates" is too strong. Randomization balances, not eliminates.
• Ensures double - blind: Randomization and double - blind are different concepts.

Answer:

Blocking Design

Question #9