Confounding is present in each of the following situations. Explain the nature of the confounding and why the conclusions are drawn may not be valid.

a) A study of proofreading compares the percent of missed errors when there is a high rate of errors (1 error in every 5 lines of text) and a low rate (1 error in every 20 lines of text). A document is prepared in which the first part has a high error rate and the second part a low error rate. Twenty people who proofread the document have any average missed error rate which is similar to both parts of the document. It is concluded that there is not a relationship between the error rate in a document and the proofreading accuracy.
b) In a geriatric study sample of people over 65 from a general community and from a retirement community are followed. At the end of two years, it is found that a larger proportion of the people continue to reside in the retirement community than in the general community. It is concluded that the retirement community living allows the elderly to maintain their independence longer than does the general community living.

Step-by-step explanation:

Hello!

A confounding variable is a factor that influences the response variable, other than the explanatory variable, that wasn't taken into account or controlled by the researcher.

For example, if you were to test the effects of a new medicine on blood pressure a confounding factor may be the diet of the individuals. If they have low or high sodium levels on their diet the blood pressure changes will not only be influenced by the medicine but also by the diet.

a.

The objective is to study if there is a relationship between the error rate in a document and the proofreading accuracy.

Several factors may be confounding in this example, here a two of them:

1. The level of education of the proofreaders, if they are highly educated persons they are more likely to find out the errors than people with lower education levels.

2. The age of the proofreaders. This factor can be confusing in several ways. One way is that younger people tend to have worse grammatic due to texting and habit of shortening expressions, so if this is the case, younger proofreaders would be less accurate than elder proofreaders.

Another way to see it is that younger minds are sharper than older minds, this way we might see that younger people might be more accurate than elder people.

Of course, this is considering that they have similar levels of education.

b.

The objective is to know if the proportion of people over 65 that continue to live in retirement communities y greater than those that live in the general community.

Confusing factors:

1. It is not taken into account whether the studied elderly had or not family. The elderly that has no family, due to impediments given by age/sickness are more likely to move to retirement communities than elderly with family. Normally families take care of their grandparents.

2. Another factor that may be decisive over living in a general community or n a retirement home is the income. Stays in retirement homes are not cheap so poor or people with low income are most likely to not move to them.

I hope it helps!