Statistics Flashcards
what is the power of a study
the probability of (correctly) rejecting the null hypothesis when it is false (no. neededto detect a significant result)
what is specificity
proportion of patients without the condition who have a negative test result.
= true negative / (true negative + false positive)
what is sensitivity
proportion of patients with the condition who have a positive test result.
= true positive / (true positive + false negative)
what is positive predictive value
probability that subjects with a positive screening test truly have the disease
true positive / true positive + false positive
what is the negative predictive value
probability that subjects with a negative screening test truly don’t have the disease
true negative/ true negative + false negative
type I error
also known as a false positive, occurs when a researcher incorrectly rejects a true null hypothesis.
type II error
false negative
occurs when a researcher incorrectly accepts a false null hypothesis.
What is the negative likelihood ratio?
Likelihood ratio for a negative test result = (1 - sensitivity) / specificity
what is absolute risk reduction
Absolute risk reduction = (Control event rate) - (Experimental event rate)
Control event rate (CER) = (Number who had particular outcome with the control/ (Total number who had the control)
Experimental event rate (EER) = (Number who had particular outcome with the intervention) / (Total number who had the intervention)
what is relative risk
Relative risk = EER / CER
Control event rate (CER) = (Number who had particular outcome with the control/ (Total number who had the control)
Experimental event rate (EER) = (Number who had particular outcome with the intervention) / (Total number who had the intervention)
what is a cross sectional study
Cross-sectional studies begin with risk factor/exposure status and compare disease prevalence to provide a snapshot. They are helpful in determining prevalence rather than investigating outbreaks or aetiologies.
what is a longitudinal study
type of observational correlational study in which repeat measurements of the same variables are taken over a prolonged period.
what is a correlational study
type of research design where a researcher seeks to understand what kind of relationships naturally occurring variables have with one another.
what is standard error of mean
Standard error of the mean = standard deviation / square root (number of patients)
good measure to determine the accuracy of the mean value of a dataset.
