I am new in this, and I am hoping for some assistance.
I have the table (attached) and need to calculate the value corresponding to Probability (-2.026). Can someone help me how to look at it from the table below? (If we have a negative Z score, how to calculate P value in the table with just positive Z scores?)
PS: I know we can look it up in negative Z score table but I wish to understand, how we can do it in this specific table?
Best Answer
In short, just subtract the values in this table above from 1.
So for a z-score of -2, with a p-value of 0.5, that gives (1- 0.9798) = 0.0202
You will get a negative z-score when $ x $ is less than $ \mu $ in the following equation:
$ z = \frac{x-\mu}{\sigma}$
As z-scores move from negative to positive they are moving from left to right on the bell curve. The z score is zero in the center. Imagine moving a vertical line across the image and asking yourself what proportion of the area under this curve is to the left of this line. At the far left it will be zero, in the middle 50% and at the far right 100%.