Answer and Explanation:
1. The experimental units are the 80 people used in the experiment. This is because an experimental unit is the smallest element of an experiment where the treatment is applied. In this case, the smallest element of the experiment subjected to the experimental treatments is the people who are participating.
2. Two treatments are used in this experiment. Experimental treatment is what you want to measure and test through the experiment. In this case, the experiment wants to test the difference between ordinary Nike shoes and Nike shoes manufactured to reduce arthritis cases, that is, there are two shoes tested, therefore, there are two treatments.
3. A potential problem presented in the project is the lack of homogeneity of the experimental units. This is because, although all the people who are participating in the experiment show first signs of knee arthritis, the researcher did not define the age, gender, height and weight that the volunteers should have to participate in the experiment. This can promote inaccurate data as these elements are also important in the onset of arthritis. To improve this problem, the researcher should have selected people of the same age, height, weight and gender.
4. A placebo-controlled, double-blind study is a study that seeks to discover the effects of an element on a person's body. In the case shown above, the element is Nike shoes that slow the progression of knee arthritis. In the case of the placebo-controlled, double-blind study, the individuals who will test the studied element will be divided into two groups. One of the groups will receive the element capable of causing changes in the body (in this case Nike shoes that delay arthritis), while the other group will receive a placebo, which is an element exactly the same as the element that promotes modifications, but has no function. . This type of study is called double-blind, because neither the researcher nor the volunteers know which group they are in. In this way, the experiment is able to present real results data, because neither the participants will be psychologically led to think that they are feeling the modifications of the tested element, nor will the researcher be led to believe that these changes actually occurred.
5. The blocking can divide 20 men and 20 women for each group. This is because the experimental block limits the randomness in the formation of experimental groups when this randomization is very difficult to achieve. Thus, when using the blocking , the researcher configures the randomness of the groups, which will facilitate the analysis of results and prevent all women from forming a group and all men from forming another group, as well as preventing groups from being formed with different amounts between men and women.