The Standard Normal model is used in hypothesis testing, including tests on proportions and on the. This means that almost 75% of the students scored lower than George and only 25% scored higher. The z-table is short for the Standard Normal z-table. It is used to find the probability that a statistic is observed below, above, or between. Multiply this number by 100 to get percentages. A standard normal table, also called the unit normal table or Z table, is a mathematical table for the values of, which are the values of the cumulative distribution function of the normal distribution. Then go to the x axis to find the second decimal number (0.07 in this case). Find the first two digits on the y axis (0.6 in our example). Finding a corresponding probability is fairly easy.
For George’s example we need to use the 2nd table as his test result corresponds to a positive z-score of 0.67. Lastly the negative score represents the corresponding values that are less than the mean. The z score for the given data is z 85-7012125. If a z-score calculation yields a negative standardized score refer to the 1st table, when positive used the 2nd table. The standard normal distribution, also called the z-distribution, is a special normal distribution where the mean is 0 and the standard deviation is 1. Table entries for z define the area under the standard normal curve to the left of the Z. If you noticed there are two z-tables with negative and positive values.
standard normal distribution table) comes handy.