Answer:
confounding variable; lowered.
Step-by-step explanation:
In the field of statistical analysis, a confounding variable is one that influences both the independent variable and the dependent variable. When an experimented is designed, the researcher wants to study the effect the independent variable has on the dependent variable. However, if there's a third variable that can influence them, it can cause a spurious correlation.
The psychologist wanted to test the effects using the new computer program (independent variable) had in helping students learn math (dependent variable). But when she divided the group in two, separating them by gender, she introduced a third variable (confounding variable) that wasn't accounted for when designing the experiment and that can influence either variable. Because of this, the internal validity of the study has been lowered.