One Tailed Test
It is a test where the alternative hypothesis (H_{1}:) is only concerned along with one of the tails of the distribution for illustration, to test a business complaint if the complaint is above the measurements of item being shorter than is essential.
For illustration, a manufacturer of a given brand of bread may state that the average weight of the bread is 500 gram but if a consumer takes a sample and weighs each of the pieces of bread and occurs to have a mean of 450 gram he will definitely complain about the bread which is underweight. The statistical analysis to be done will concentrate on the left tail of the normal distribution whether one will have to establish whether 450 gram being less than 500 gram is statistically significant. Therefore such a test is referred to as one tailed test.
On the other hand the test might copulate on the right hand tail of the normal distribution when this occurs the major complaint is likely to do along with oversize items bought. Hence the test is termed as one tailed as the focus is on one end of the normal distribution.
Number of standard errors
Two tailed test
One tailed test
5% level of significance
1.96
1.65
1% level of significance
2.58
2.33