QC Equations

Question 1

Sensitivity

Answer 1

(TP / (TP + FN)) * 100

Question 2

Specificity

Answer 2

(TN / (TN + FP)) * 100

Question 3

Positive Predictive Value

Answer 3

(TP / (TP + FP)) * 100

Question 4

Negative Predictive Value

Answer 4

(TN / (TN + FN)) * 100

Question 5

Efficacy

Answer 5

((TP + TN) / Total n) * 100

Question 6

Prevalence

Answer 6

((TP + FN) / Total n) * 100

Question 7

Bias

Answer 7

Average of the differences between new and old methods (new - old)

Question 8

SD Diff

Answer 8

SD of the differences between new and old methods (new - old)
-note: NOT difference of SDs

Question 9

How is R calculated from R^2?

Answer 9

Square root R^2

Question 10

What value of R is acceptable?

Answer 10

R >= 0.95

r = 1 is perfect correlation
r = 0 is perfect randomness

Question 11

Proportional Error (PE)

Answer 11

(Slope - 1) x 100

Question 12

F Test

Answer 12

Variance (larger) / Variance (smaller)

Variance = SD^2

Question 13

F Critical

Answer 13

Look for degrees of freedom on F table

-rows and columns for degrees of freedom correspond to n - 1 for each data set

Question 14

Paired T Test

Answer 14

(Abs (bias) * SQRT (n)) / SD diff

Question 15

T Critical

Answer 15

Look for degrees of freedom on T table

-degrees of freedom = n - 1

Question 16

Passing F test value. What happens when F test fails?

Answer 16

F Test < F Critical

Failing F test means we do not need to do the T test

Question 17

Passing T test value

Answer 17

T Test < T Critical

Question 18

The Y-intercept of a line is also known as…

Answer 18

Constant Error

Question 19

Coefficient of Variation (CV)

Answer 19

(SD / mean) * 100

Question 20

Standard deviation (SD)

Answer 20

Square root ((E (x - mean)^2) / (n - 1))

Question 21

% Error

Answer 21

Abs ((measured - assigned) / assigned) * 100

Question 22

Median

Answer 22

Middle number of organized data set (smallest to largest)

Question 23

Mode

Answer 23

Most frequently appearing number

Question 24

How to determine the probability of X between two Z-scores

Answer 24

(Difference between values of the 2 Z-scores) * 100

Question 25

How to determine the number of values that fall between two values using the Z score

Answer 25

(Difference between values of the 2 Z-scores) * total n

-note - don’t need to convert probability into % since we are multiplying by it

Question 26

Variance

Answer 26

SD^2

Question 27

Z score

Answer 27

(x - mean) / SD

Question 28

1 SD probability

Answer 28

68.2%

Question 29

2 SD probability

Answer 29

95.5%

Question 30

3 SD probability

Answer 30

99.7%