Laboratory Statistics

Question 1

Measures of Center

Answer 1

Mean, Median, Mode

Question 2

Measures of spread

Answer 2

SD, Cv, Range

Question 3

Average or arithmetic mean

Answer 3

Mean

Question 4

Midpoint of a data set after the values have been rank-ordered

Answer 4

Median

Question 5

Most frequently occurring value in a data set

Answer 5

Mode

Question 6

Distribution of data points around the mean

Answer 6

SD (Standard Deviation)

Question 7

Best indicator of precision

Answer 7

CV (Coefficient of Variation)

Question 8

Difference between the highest and lowest values

Answer 8

Range

Question 9

Data points are distributed symmetrically around the mean (bell-shaped curve) with most values close to the center

Answer 9

Gaussian/Normal Distribution

Question 10

Done to confirm the validity of an existing or published RI for an analyte

Answer 10

Verifying a reference interval

Question 11

How many study individuals and what percent is needed for the RI to be adopted in verifying a reference interval?

Answer 11

20; less than or equal to 10%

Question 12

Done when there is no exisiting RI for an analyte or when the transference studies fail

Answer 12

Establishing a reference interval

Question 13

How many study individuals and what percent confidence interval is base for the RI in establishing a reference interval?

Answer 13

120; 95%

Question 14

First step in method evaluation; usually done by running 2 control materials twice a day for a period of 10 days

Answer 14

Precision study

Question 15

Involves spiking a sample with a known amount of an analyte and determining how much of it can be detected by the method in the presence of other compounds in the matrix

Answer 15

Recovery study

Question 16

Compares the means of two groups o data or the accuracy of two methods

Answer 16

T test

Question 17

Compares the SD of two groups of data or the precision of two procedures

Answer 17

F test

Question 18

Used to compare two methods using the best fit line through the data points

Answer 18

Linear regression

Question 19

Ability of a method to detect the smallest concentration of an analyte

Answer 19

Analytical sensitivity

Question 20

Ability of a method to detect only the analyte of interest

Answer 20

Analytical specificity

Question 21

Ability of a test to detect a given disease or condition; proportion of individuals with the disease who have a positive test result

Answer 21

Diagnostic sensitivity

Question 22

Ability of a test to detect the absence of a given disease or condition; proportion of individuals with no disease who have a negative test result

Answer 22

Diagnostic specificity

Question 23

Probability that a positive test result indicates disease; proportion of individuals with a positive result who truly have the disease

Answer 23

Positive predictive value

Question 24

Probability that a negative test result indicates absence of disease; proportion of individuals with a result who truly do not have the disease

Answer 24

Negative predictive value