Stem-and-Leaf plot is a method of organizing numerical data in order of place value. The 'ones digit' and the 'tens digit and greater' of each data item is separated as leaves and stems respectively. The stem-and-leaf plot below shows the number of students enrolled in a dance class in the past 12 years.
Vaccination with live viruses may interfere with TST reactions. For persons scheduled to receive a TST, testing should be done as follows: Either on the same day as vaccination with live-virus vaccine or 4-6 weeks after the administration of the live-virus vaccine. At least one month after smallpox vaccination.
The QuantiFERON-TB Gold requires only a simple blood test. The patient, therefore, has no need to return to interpret skin test results, there is less chance of interpretation error, and far fewer changes of returning false positives when compared to the PPD. Better yet, results are returned in around 24 hours.