How To Read Z Score Table

A z score is simply defined as the number of standard deviation from the mean.

How to read z score table. Go to the row that represents the ones digit and the first digit after the decimal point the tenths digit of your z value. To find out the z score we use the formula. A z score of zero means that the data value equals the mean. If a z score calculation yields a negative standardized score refer to the 1st table when positive used the 2nd table. To use the z score table start on the left side of the table go down to 1 0 and now at the top of the table go to 0 00 this corresponds to the value of 1 0 00 1 00.

Find the first two digits on the y axis 0 6 in our example. For george s example we need to use the 2nd table as his test result corresponds to a positive z score of 0 67. The corresponding area is 0 8621 which translates into 86 21. The z score can be calculated by subtracting mean by test value and dividing it by standard value. Z score 800 700 180.

Here you want the probability that z is between 1 0 and 1 0. Z x μ σ 50 50 2 0 2 0. On some z tables you will find that the area corresponding to 1 09 z score is 0 3621. Intersect the row and column from steps 1 and 2. Go to the column that represents the second digit after the decimal point the hundredths digit of your z value.

So z x μ σ where x is the test value μ is the mean and σ is the standard value. Z score x µ σ. Then we look up a remaining number across the table on the top which is 0 09 in our example. First we find the first two digits on the left side of the z table. To find the probability that z is between two values use the z table to find the probabilities corresponding to each z value and then find the difference between the probabilities.

In other words p z 1 53 0 0630. Z score 0 56. Finding a corresponding probability is fairly easy. Roughly 84 13 of people scored worse than him on the sat. For example consider a data set with a mean of 50 and a standard deviation of 2.