Paper must be at least 500 words, paper must include a summary and detailed explanation
From definition, Internal Validity is said to be the approximate truth about inferences on the basis of cause-effect. control groups acts as a threat to internal validity in that it assigns a research a standard value which is used as the reference point and hence leading to biases on a finding as the control group value may be very far from the research intended.
types of threats to internal validity
selection. this leads to biases in the study which hence leads to wrong comparison and hence leading to wrong conclusion.
history: history accounts for the event in the past contest and if used may lead to wrong conclusion as different parameters of an event keeps on changing with rime.
testing: testing leads to wrong results as the outcome solemnly depends on the moods of the respondents and hence can result to bias results.
internal validy requires high level of accuracy and independence so as to allow the free comparison of data