# Quality Assurance Flashcards

Parameter

The whole population

Statistic

Sample of the population

Population

set of homogeneous items or events that is of interest for some question or experiment.

Sample

A sample is a smaller group of members of a population selected as a representative of the population.

Sample is biased

Random Sample

Randomly means that every member of the target population has an identical chance of being included in the sample. In other words, the method you use for selecting your sample can not be biased.

quality

Documented data use of statisticial calculations to compare lab data against other confirmed means of testing

what are the 2 medicine statistical tests

Reference test (Gold standard) Comparison test (Procedure to be validated)

when does a test become gold standard?

When it is the most consistent and most accurate test for a particular disease

What is a comparison test

Any other testing procedure, competing technology or variation from the gold standard

Making statistical indices more intuitive

Realize that all indices start with a presumption that the Gold Standard is perfect

Pay particular attention to the English of the statistical terminology

Pay close attention to the labels and layout of any table of data

Golden rule

For all purposes of statistical indices, the assumption is that the gold standard s perfect

If the results of a test match the results of a gold standard

Test=true

If the results of a test do not match the results of a gold standard test

Test=false

Both comparison and gold standard test are attempting to do what?

Predict the presence of disease

If the result is positive

it means that the test predicted the presence of disease

If the result was negative

Test predicted the absence of disease

True

is when the test results match the gold standard

False

is when the test results do not match the gold standard

True Positive

The test is correct (T) because it matches the gold standard and the test is positive for disease (P)

True Negative

The test is correct (T) because it matches the gold standard and the test is negative for disease (N)

False Positive

The test is incorrect (F) because it does not match the gold standard and the test is positive for disease (P)

False negative

The test is incorrect (F) because it does not match the gold standard and the test is negative for disease (N)

Gold standard

Assumed to be perfect

Number of tested Patients with disease

Have disease=TP+FN

Patients without disease

No disease=TN+FP

Number of tested patients in the population that the test predicts to have the disease

Test positive: TP+FP

Number of tested patients in the population that the test predicts do not have the disease

Test negative: TN+FN

Sensitivity

Implies the ability of a test to detect disease

Times the test correctly predicted disease divided by al of the the times the disease really does exist

Sensitivity equation

TP/TP+FN (*100%)

Specificity

Refers to the ablity of a test to detect the absence of disease relative to the number of people who in reality do not have disease

Specificity equation

TN/TN+FP (*100%)