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need12 · Jul 20, 2010, 11:09 AM

how to know whether to perform one tailed test or two tailed test ?

in this example:
the average weekly earnings of a worker were $424. To know if wages, on average, have gone up since that time. To test this, you sample 64 production workers, and determine that their average salary is $432.69, with a sample standard deviation of $33.90. Use a 0.05 level of significance .carry out test .
is it t test or z test ? How would we know
is this one tailed or two tailed test
I guess its one tailed test .is that correct?(as it is seeking some increase )
please help me out thanks in advance

galactus · Jul 20, 2010, 01:35 PM

Say the problem statement above said, "to know if wages, on average, were 432.69". This is like an 'equals to'. In this case, we test rather the wages have gone up. Therefore, a right tailed test.

need12 · Jul 20, 2010, 05:32 PM

Originally Posted by galactus

Say the problem statement above said, "to know if wages, on average, were 432.69". This is like an 'equals to'. In this case, we test rather the wages have gone up. Therefore, a right tailed test.

Right tailed test is same as one tailed test right?

galactus · Jul 20, 2010, 05:37 PM

Originally Posted by need12

right tailed test is same as one tailed test right?

Yes. One tailed can be either left or right tailed.

need12 · Jul 21, 2010, 09:07 AM

Originally Posted by galactus

Yes. One tailed can be either left or right tailed.

Thank you for the reply