Glossary - Research Basics and Terminology

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S

Sensitivity

(Last edited: Tuesday, 14 March 2017, 8:55 AM)

Measure of a test’s ability to correctly detect people with the disease
Sensitivity and specificity are inversely proportional: when sensitivity increases, specificity decreases and vice versa
Example:

A sensitivity of 97.5% in mammography screening means that every woman with a tumor will be correctly detected in 97.5% of the cases. 2.5% might have a tumor, but cannot be identified through the screening.

Further information: Understanding and using sensitivity, specificity and predictive values.

Example for using sensitivity in a study: Sensitivity and specificity of mammography and adjunctive ultrasonography to screen for breast cancer in the Japan Strategic Anti-cancer Randomized Trial (J-START): a randomised controlled trial.

Keyword(s):

Skewed Distribution

(Last edited: Tuesday, 14 March 2017, 8:55 AM)

Asymmetrical shape of distribution
Types

Skewed to the left: negative skew (long tail on the negative side of the tail)
Skewed to the right: positive skew (long tail on the positive side of the tail)

Keyword(s):

Specificity

(Last edited: Tuesday, 14 March 2017, 8:55 AM)

Measure of a test’s ability to correctly identify people who do not have the disease
Sensitivity and specificity are inversely proportional: when sensitivity increases, specificity decreases and vice versa
Example:

A specificity of 95.0% in mammography screening means that 95.0% of the women tested are correctly identified as not having a tumor.

Further information: Understanding and using sensitivity, specificity and predictive values

Keyword(s):

Standard Deviation

(Last edited: Tuesday, 14 March 2017, 8:55 AM)

Measure of the spread/dispersion of a set of observations
Square root of the variance
Formula: $s= \sqrt{(\sum\nolimits_{i=1}^n(x_i- \mu)^2)/(n-1) }$
Example:

Set of numbers: 3,4,5,5,5,6,7

Keyword(s):

Statistically Significant

(Last edited: Tuesday, 14 March 2017, 8:55 AM)

Result that is unlikely to have happened by chance
It is assessed by the p-value

Keyword(s):