Clinical Epidemiology 3 - Abnormality Flashcards Preview

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Flashcards in Clinical Epidemiology 3 - Abnormality Deck (12)
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1

Degree to which the data measure what they were intended to measure

Validity / Accuracy

2

The extent to which repeated measurements of a stable phenomenon by different people and instruments get similar results

Reliability/ Precision

3

The absolute value of the average difference of individual values from the mean

Standard Deviation

4

Measure of central tendency which is well suited for mathematical manipulation

Mean

5

Measure of central tendency not easily influenced by extreme values, good for skewed data

Median

6

Frequency distribution of repeated measurements of the same physical object by the same instrument

Normal Distribution

7

What percent of the observations in a normal distribution fall within 1 standard deviation from the mean? (-1 to 1)

66.66% (2/3)
To be exact, 68%

8

What percent of the observations in a normal distribution fall within 2 standard deviations from the mean? (-2 to 2)

95%

9

What percent of the observations in a normal distribution fall within 3 standard deviations from the mean? (-3 to 3)

99%

10

Statistical definition of normality?

2 standard deviations from the mean

11

Three definitions of abnormality in clinical epidemiology

Unusual (Statistically more than 2 SDF away)
Associated with disease
Treating condition leads to better outcome

12

Phenomenon when abnormal test result is repeated, the second result is often closer to normal?

What is logic behind it?

Regression to the Mean

Abnormal test result is usually "high" (many SD away from mean) so on repeat test, higher probability of being closer to normal value