Stats+Research Flashcards
What values can the correlation coefficient range between?
Correlation coefficient can range from -1 to +1
What value is the correlation coefficient represented by?
r
What are the values of the categories of degree of correlation?
0-0.2 negligible
- 2-0.5 weak
- 5-0.8 moderate
- 8-1 strong
What does standard deviation measure?
Spread of a set of observations - variability of the obseervations
What is the formula for standard deviation?
square root of variance
What does a low standard deviation mean?
Data points tend to be very close to the mean
What does a high standard deviation mean?
Data points tend to be spread out over a large range of values
Is variance expressed in the same units as the data?
No
As the SD increases what happens to the SEM?
increases
As sample size increases what happens to the SEM?
Decreases
What’s the SEM?
A measurement of the precision of the sample mean as an estimate of the population mean
What is snowball sampling?
identifying participants with certain characteristics and getting them to identify more participants
What is Absolute risk reduction?
Absolute risk reduction is the difference in risk of a given event between two groups.
Formula = CER - EER
What is the confidence interval?
Confidence interval is the range of values within which one can be 95% certain that the true reference population value lies
What is the NNT?
Number needed to treat is the number needed to treat to get one good outcome or to prevent one additional outcome
Formula = 1/ARR
What is the relative risk?
Relative risk is the ratio of the risk of a given event in one group of subjects compared with another group
Relative risk = EER/CER
Relative risk reduction = ARR (CER-ERR)/CER
What is the relative risk reduction
Relative risk reduction is the proportion of the initial or baseline risk that was eliminated by a given treatment or by avoidance of exposure to a risk factor
What are case-control studies ideal for?
Rare diseases/outcomes
-partcularly useful for situations where there is a long time period between exposure and outcome
What type of bias are case-control studies at risk of?
Recall bias
What is face validity?
The extent to which a test measures what it’s supposed to measure
What is reliability?
How consistent a test is on repepeated measurements
What is predictive validity?
The extent to which a test is able to predict something it should theoretically be able to predict
What is inter rate reliability?
The level of agreement between assessmentsmade by two or more raters at the same time
What is contruct validity?
The extent to which a test measures a theoretical connstruct by a specific measuring device or procedure