Why is it important to have a control group in an experimental investigation?
to show what happens when the dependent variable is not changed
to see how the dependent variable changes the independent variable
to compare the results when the independent variable is not involved
to allow the researchers
to change the dependent variable as they wish

to compare the results when the independent variable is not involved

is the correct answer

to compare the results when the independent variable is not involved

Explanation:

Dependent variable depends on the independent variable. Independent variable is the one that is being tested in a science experiment to test how it is affecting the dependent variable.

In a control group in an experimental investigation the independent variable is omitted. Thus the goal is to test if the dependent variable shows any change in the absence of the independent variable.

here is table 2-2:

country

percent of eligible voters that voted

rank

united states

44.9%

138

canada

60.1%

107

costa rica

84.6%

14

hungary

66.9%

82

japan

57.0%

118

egypt

27.7%

159

south africa

85.5%

10

ans is no, the data set cannot be plotted as a single circle graph