Laboratory Statistics

Question 1

AVERAGE or arithmetic mean

Answer 1

mean (x̄)

Question 2

MIDPOINT of data

Answer 2

median

Question 3

most FREQUENTLY occurring value in a data set

Answer 3

mode

Question 4

distribution of data points AROUND THE MEAN

Answer 4

standard deviation

Question 5

square of std deviation

Answer 5

variance

Question 6

best indicator of PRECISION
↓CV ↑precision

Answer 6

coefficient of variation

Question 7

difference between the HIGHEST and LOWEST values

Answer 7

range

Question 8

Bell-shaped curve

Answer 8

Gaussian/Normal Distribution

Question 9

empirical rule of Gaussian

Answer 9

68% - 95% - 99.7%

Question 10

± 1s

Answer 10

68%

Question 11

± 2s
confidence interval

Answer 11

95%

Question 12

± 3s

Answer 12

99.7%

Question 13

CV rule of thumb

Answer 13

<10%

Question 14

control values before qc data analysis

Answer 14

minimum of 20

Question 15

pair of medical decision points that span the LIMITS OF RESULT expected for a defined HEALTHY POPULATION

Answer 15

reference interval

Question 16

don to CONFIRM VALIDITY of an EXISTING OR PUBLISHED RI for an analyte

Answer 16

verifying RI

Question 17

VERIFYING RI
- requires at least __ study individual
- RI is adopted if __% of the subjects fall outside the range

Answer 17

20
<10%

Question 18

done when there is NO EXISTING RI for an analyte or when transference studies fail

Answer 18

establishing RI

Question 19

ESTABLISHING RI
- requires __ study individuals
- RI is set based on the __%

Answer 19

120
95%

Question 20

x̄ ±2S

Answer 20

confidence interval

Question 21

done by running TWO CONTROL materials TWICE A DAY over a 10-DAY PERIOD

Answer 21

precision study

Question 22

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 22

recovery study

Question 23

compares the MEAN of two groups of data or the ACCURACY of two methods

Answer 23

T test

Question 24

compares the SDs of two groups of data or the PRECISION of two procedures

Answer 24

F test

Question 25

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

Answer 25

linear regression

Question 26

• independent variable
• standard/reference method

Answer 26

X

Question 27

• dependent variable
• new method

Answer 27

Y

Question 28

AXIS

Answer 28

Abscissa
X-axis
Independent variable
Standard/reference method

Question 29

VOYD

Answer 29

Vertical / X-axis
Ordinate
Y-axis
Dependent variable

Question 30

ability of a method to detect the SMALLEST CONCENTRATION of an analyte

Answer 30

analytical sensitivity

Question 31

ability of a method to detect ONLY the ANALYTE OF INTEREST

Answer 31

analytical specificity

Question 32

• ability of a test to detect a given DISEASE or CONDITION
• proportion of individuals with the DISEASE who have a positive test result

Answer 32

diagnostic sensitivity

Question 33

• ability of a test to detect a given ABSENCE OF A GIVEN DISEASE or CONDITION
• proportion of individuals with NO DISEASE who have a negative test result

Answer 33

diagnostic specificity

Question 34

• PROBABILITY that a positive test result indicates DISEASE
• proportion of individuals with POSITIVE results who truly have the disease

Answer 34

Positive Predictive Value

Question 35

• PROBABILITY that a negative test result indicates ABSENCE OF DISEASE
• proportion of individuals with NEGATIVE results who truly do not have the disease

Answer 35

Negative Predictive Value

Question 36

TP/TP+FNx100

Answer 36

%Sensitivity

Question 37

TN/TN+FPx100

Answer 37

%Specificity

Question 38

TP/TP+FPx100

Answer 38

%PPV

Question 39

TN/TN+FNx100

Answer 39

%NPV