How To Read Z Score Table
So z x μ σ where x is the test value μ is the mean and σ is the standard value.
How to read z score table. Finding a corresponding probability is fairly easy. Find the first two digits on the y axis 0 6 in our example. Go to the row that represents the ones digit and the first digit after the decimal point the tenths digit of your z value. The corresponding area is 0 8621 which translates into 86 21. Z score x µ σ.
On some z tables you will find that the area corresponding to 1 09 z score is 0 3621. A z score is simply defined as the number of standard deviation from the mean. How to use the z table. There are two methods to read the z table. A z score of zero means that the data value equals the mean.
Z x μ σ 50 50 2 0 2 0. Use z table to see the area under the value x in the z table top row and the first column corresponds to the z values and all the numbers in the middle corresponds to the areas. 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. For example a z score of 1 53 has an area of 0 0630 to the left of it. For george s example we need to use the 2nd table as his test result corresponds to a positive z score of 0 67.
For example consider a data set with a mean of 50 and a standard deviation of 2. Z score 800 700 180. If a data value also is 50 then the z score is. Z score observed value mean of the sample standard deviation. In this case it is 1 0.
To find out the z score we use the formula. Then find the value where the row for 1 0 intersects with the column for 0 00 which is 0 8413. Intersect the row and column from steps 1 and 2. First use the z table to find the value where the row for 1 0 intersects with 0 00 which is 0 1587. In other words p z 1 53 0 0630.