In: Statistics and Probability
No, it not necessary to use 5 % level of significance in every time.
We can take 0.01, 0.04, 0.03 or any value. Level of significance means error term how much error you can accept in your problem.
But most of time we use 5% level of significance this means that the finding of your hypothesis is 95% chance of being true. 95% or 0.95 is no any Statistical standared value.
For more accurate result you can use level of significance 0.001 this means that finding as a 99.9% chance of being true. But chances of rejecting a null hypothesis is increased. If we use 0.1 level of significance this means 90% chance of being true. That means chances of accepting of hypothesis is increased but result will be poor.
So most of time 5% level of significance true.
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