hi every one love to have you all here,
what is z-distribution? intuitively what does that tell us? please understand before using the table.
the z-distribution is a normal standard distribution with mean 0 and standard deviation 1 , which has a probability or frequency distribution on y-axis and observations with standard deviation of 1 on x-axis,
so, by using the z-distribution we can get the confidence level so that we can calculate confidence interval. that is how news channels and some private firm use this to estimate the winners in exit polls
when to apply?
when we know the standard deviation of the population, we use this for infer the population parameters, but, infact, in real world problems we are generally not given any standard deviation of the population..
procedure to identify the z-score
1. identify and decide the level of significance.
2. find the appropriate test , one tail above , one tail below or two tailed test.
2. go to the z-distribution table and mark the required level of significance on the column headings and look for the z-value in respective location for the required level of significance and required test.
z-distribution table
|
Critical Values (Z) |
Level of
Significance |
||||
|
1% |
2% |
4% |
5% |
10% |
|
|
Two Tailed |
±2.56 |
±2.32 |
±2.05 |
±1.96 |
±1.64 |
|
Right tailed |
+2.32 |
+2.05 |
+1.75 |
+1.64 |
+1.28 |
|
Left tailed |
-2.32 |
-2.05 |
-1.75 |
-1.64 |
-1.28 |
note: please feel free to ask any doubts in comment section below, love to have suggestion from you
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