Data Interpretation

Question 1

How do we get reference intervals?

Answer 1

Fluctuations in a healthy population

Question 2

What is the definition of health in veterinary medicine?

Answer 2

Absence of disease

Wellbeing of the animal

Question 3

What are the categories to define a population?

Answer 3

Species or breed

Age

Location

Climate

Season

Question 4

In general, how much of the healthy population falls OUTSIDE the reference interval?

Answer 4

5%

(2 standard deviations from the mean)

Question 5

What are the 3 phases errors occur in data interpretation?

Answer 5

Pre-analytical: before the sample gets to the analyzer. (most common source or error)

Analytical: issue with the machine

Post-analytical: uploading, transcription, interpretation

Question 6

Instrument function, knowledge and training on the instrument, and manuals of standard operating procedure are all factors that can influence what phase of error in data interpretation?

Answer 6

Analyzer error

Question 7

The probablility that a diseased patient tests positive for the disease is determined by the test’s ______.

Answer 7

Sensitivity

Question 8

If a test is 99% sensitive, how many patients with the disease will test positive?

How many patients with the disease will test negative?

Answer 8

99 patients with the disease will test positive (true positive)

1 patient with the disease will test negative (false negative)

Question 9

If 93 or 100 animals known to have a disease test positive for the disease, and 7 of 100 animals known to have a disease test negative for the disease, what is the sensitivity of the test used?

Answer 9

Sensitivity = TP/(TP + FN)

= 93/(93+7)

= 93% sensitivity

*True positives divided by all patients that HAVE the disease (true positives and false negatives)

Question 10

The probability that a healthy patient tests negative for a disease refers to what feature of the test?

Answer 10

Specificity

Question 11

If 87 of 100 healthy patients test negative for a disease, or 13 out of 100 healthy animals test positive, what is the specificity of the test?

Answer 11

Specificity = TN/(TN+FP)

=87/(13+87)

=87%

*Healthy patients (true negatives) / All animals that don’t have the disease (true negatives and false positives)

Question 12

What is the formula for determining the the prevalence of a disease in a population?

Answer 12

Prevalence = (TP + FN)/ Entire Population

*All positives (true positives and false negatives) divided by the entire population.

Question 13

Confidence in a positive test result is high is that test has a high ____ _____ ____.

Answer 13

Positive predictive value

*This test will have very few false positives

Question 14

Confidence in a negative test result is high when the test has a high _____ _____ _____.

Answer 14

Negative predictive value

*This test will have very few false negatives