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.
To perform two-step testing, a second skin test is placed 1-3 weeks after the initial skin test, if the first test is negative. If the second test remains negative, the person is presumed to be negative for latent tuberculosis, and any subsequent positive tests are the result of new infection. If the second test turns positive, this is a boosted response from prior TB infection.