In order to study the effects of watching violent programs on children's aggressiveness, a researcher observes children's behavior after they watch 30 minutes of violent programs on television. The researcher concludes that television violence causes aggressiveness. A problem in this research is that:.

Absence  of control group.

Explanation:

A control group is a term that decribes a scientific experimention in which a group is carved out separately from the rest of the subjects in an experiment, such that, the independent variable being tested or under analysis will not have an influence on the results.

This helps to remove the independent variable's effects on the experiment and can help rule out alternative explanations of the experimental results.

Control groups can also be separated into two other types: positive or negative.

Positive control groups are groups where the conditions of the experiment are set to guarantee a positive result.

While

Negative control groups are groups where the conditions of the experiment are set to cause a negative outcome.

However, in this case, the research has a problem of absence of control group, because there is no Negative control group to show whether, the outcome of the research is negative; no group to compare with, so as to explain whether watching violence programs causes aggressiveness in children or not.

In clear terms, there should be other group in the research experiment, that did not watch violence programs, then researcher can compare the observation from the two groups to make a conclusion.

Else, there is problem of no control group.

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