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Two-tailed Critical Z-value Example. For a two-tailed z-test, you need to divide your alpha in half because the test splits the area between the upper and lower tails. For a significance level of 0.05, look for the area of 0.05 / 2 = 0.025 in the negative z-table.
What is a Z-Table? The z-table is known by several names, including z score table, normal distribution table, standard normal table, and standard normal distribution table. Z score is the value of the standard normal distribution.
A Statistical Tables 135 Standard Normal Z Distribution Probabilities −3 −2 −1 0 1 2 3 Z Lower-tail probability: P(Z < z) z 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0 ...
Page 1 of 1 of C:\data\StatPrimer\z-two-tails.doc Last printed 4/7/2007 10:47:00 AM Two tails of Z Entries in the table represent two-tailed P values for z statistics
Using two Z tables makes life easier such that based on whether you want the know the area from the mean for a positive value or a negative value, you can use the respective Z score table. If you want to know the area between the mean and a negative value you will use the first table (1.1) shown above which is the left-hand/negative Z-table.
# Display z table ztable = zTable (zmin = 1, zmax = 3) with pd. option_context ('display.max_rows', None, 'display.max_columns', None): display (ztable) 0.00 0.01
3 wrz 2024 · R command. Z <- seq(-4,4, by=.1) pnorm(c(Z), mean=0, sd=1, lower.tail=FALSE) This page titled A.2: Table of Z of standard normal probabilities is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Michael R Dohm via source content that was edited to the style and standards of the LibreTexts platform.
