Critical value

From Wikipedia, the free encyclopedia

Suppose the data can be realized from an N(0,1) distribution. For example, from the Z-table for standard normal distribution, we know that P(Z ≥ 1.96) = 0.025, Z0.025 = 1.96 (p = 0.025 is the tail probability). Also, by the symmetry of the standard normal distribution, P(Z ≤ -zp) = P(Z ≥ zp) = p.

Critical value may refer to:

  • In statistical hypothesis testing, the critical values of a statistical test are the boundaries of the acceptance region of the test.[2] The acceptance region is the set of values of the test statistic for which the null hypothesis is not rejected. Depending on the shape of the acceptance region, there can be one or more than one critical value.
  • In medicine, a critical value or panic value is a value of a laboratory test that indicates a serious risk to the patient.[3] Laboratory staff may be required to directly notify a physician or clinical staff of these values.


  1. ^ do Carmo, Manfredo Perdigão (1976). Differential Geometry of Curves and Surfaces. Prentice Hall. ISBN 0-13-212589-7.
  2. ^ Hughes, Ann J.; Grawoig, Dennis E. (1971). Statistics: A Foundation for Analysis. Reading, Mass.: Addison-Wesley. p. 191. ISBN 0-201-03021-7.
  3. ^ "Laboratory Critical/Panic Value List". Stanford Health Care.