How To Read Z Score Table
The z score can be calculated by subtracting mean by test value and dividing it by standard value.
How to read z score table. For george s example we need to use the 2nd table as his test result corresponds to a positive z score of 0 67. Roughly 84 13 of people scored worse than him on the sat. To find out the z score we use the formula. Z score 800 700 180. Intersect the row and column from steps 1 and 2.
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. Then find the value where the row for 1 0 intersects with the column for 0 00 which is 0 8413. In this case it is 1 0. Go to the column that represents the second digit after the decimal point the hundredths digit of your z value. In other words p z 1 53 0 0630.
A z score is simply defined as the number of standard deviation from the mean. Z score observed value mean of the sample standard deviation. First we find the first two digits on the left side of the z table. For example a z score of 1 53 has an area of 0 0630 to the left of it. 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.
For example consider a data set with a mean of 50 and a standard deviation of 2. On some z tables you will find that the area corresponding to 1 09 z score is 0 3621. If a z score calculation yields a negative standardized score refer to the 1st table when positive used the 2nd table. The corresponding area is 0 8621 which translates into 86 21. How to use the z table.
Z score 0 56. Using the above data we need to first standardize his score and use the respective z table before we determine how well he performed compared to his batch mates. There are two methods to read the z table. Here you want the probability that z is between 1 0 and 1 0. Z score x µ σ.