A medical researcher is interested in how weight gain in children from third-world countries is affected by the source of protein (fish,roots and tubers,or nuts and oilseeds)and by level of protein intake (low,defined as less than 0.56 grams per kilogram of weight,or high).The researcher wants to test the relative efficacy of each protein source,controlling for the level of protein intake but not testing it as the main variable of interest.For this purpose,she classifies a group of children in an impoverished village in a third-world country into either high or low protein intake.Then,the researcher randomly assigns 50 children from each category to a group where the children will receive food once a day that will emphasize one of the three protein sources.You can assume that the total level of protein intake is not affected (it's effects take a longer time to show and depend largely on the other meals the children have at home).The researcher's experimental design is a ______.
A) normalized block design
B) completely randomized design
C) factorial design
D) random block design
E) partially randomized design

Question

Quizplus · Accepted Answer

A random block design is an experimental design in which the subjects are first divided into blocks, and then the treatments are randomly assigned to the subjects within each block. This design is used to control for the effects of extraneous variables that may affect the results of the experiment. In this case, the researcher is controlling for the level of protein intake by dividing the children into two blocks (high and low protein intake) and then randomly assigning the children within each block to the three protein source groups.

A Medical Researcher Is Interested in How Weight Gain in Children