Respuesta :
a threat to coccurs only if a potential design confound varies systematically with the independent variable.
When a study has internal validity, you can be sure that the independent variable and not another variable caused the dependent variable. Therefore, a study that has a high level of internal validity allows for cause and effect findings. A confounding variable, which is any variable other than the independent variable that 1) co-varies with the independent variable and 2) may be an alternative cause of the dependent variable, poses the biggest threat to internal validity.
To know more about internal validity :
https://brainly.com/question/2813609
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