# Threats to Internal Validity Flashcards

What is chance?

Where we have the pressence of random error which is inherent in all measurement.

More error is not good

How do we measure chance?

Using the p-value

What is a P value?

Probability representing the strength of evidence to support hte null hypothesis

What is a Large P value of >0.05 represent?

Supports the Null hypothesis hence their is no statistically significant difference between to two groups

What is a samll p value of <0.05 represent?

We reject the null hypothesis hence there is a statistical significance between the two groups’ results

What is the overall theme of what is the p value really saying?

The probability the results are due to chance rather than a real treatment effect

How do we deal with chance?

Increase sample size

Recognize the extent via statistics and interpret the results accordingly

What is important with respect to chance and statistical significance?

Does not necessarily mean clinical significance

What is confounding?

When some factors other than the intervention or exposure under study, influence the overall outcome

What are the ways we can help with confounding?

Randomization

Stratification

Matching

What is randomization?

Ensures groups are similar in all aspects, known and unknown factors

What is stratification?

Where we attempt to force an equal distribution of people from similar groups (Regina and Regina, Sask/Sask)W

What is matching

Where we try and match people in the test/placebo group based on sex, age, and similar characteristics

What is bias?

Problems with the way a study was designed conducted or analyzed that leads to incorrect results or conclusions

What is selection bias?

Problems with how the study subject were selected