what are the difference between directional and non-directional test
Answers
Answer:
There are 2 types of hypothesis:i) Directionalii) Non - Directional
Directional hypothesis are those where one can predict the direction (effect of one variable on the otheras 'Positive' or 'Negative')for e.g: Girls perform better than boys ( 'better than' shows the direction predicted )Non Directional hypothesis are those where one does not predict the kind of effect but can state arelationship between variable 1 and variable 2.for e.g. There will be a difference in the performance of girls & boys (Not defining what kind of difference)You can choose any of these hypothesis based on the kind of results you expect at the end.
Examples of : Directional and non directional
I would expect a non-directional hypothesis to be one which leaves it to the reader's imagination tothink about what the end result will be.A directional hypothesis is the opposite, whereby one tries to convince others that his hypothesis iscorrect, instead of letting people judge for themselves.directional implys you are "hypothesising" and predicting the outcome before you conduct yourresearch.None directional implies you don't know which way it will go. Its more hypothetical.2)
hether you frame your alternative hypothesis, H
a
, as one-sided (directional) or two-sided (non-directional) is really up to you, but should be decided before you look at the data. It will affectthe calculation of your p-value and ultimately your conclusions from the test. In most cases therewill be a sound, obvious reason for choosing one or the other.For example, if you were testing the effectiveness of a new anti-cholesterol drug you'd probablyonly be interested in testing whether the average of the experimental group was
lower
than thecontrol group. So H
a
is directional, or one sided. If on the other hand you were testing, forexample, whether a Group A performed better on a test than Group B, your H
a
would be that theaverage of Group A does not equal Group B. That is, you're not sure, before you run the test,
There are 2 types of hypothesis:i) Directionalii) Non - Directional
Directional hypothesis are those where one can predict the direction (effect of one variable on the otheras 'Positive' or 'Negative')for e.g: Girls perform better than boys ( 'better than' shows the direction predicted )Non Directional hypothesis are those where one does not predict the kind of effect but can state arelationship between variable 1 and variable 2.for e.g. There will be a difference in the performance of girls & boys (Not defining what kind of difference)You can choose any of these hypothesis based on the kind of results you expect at the end.
Examples of : Directional and non directional
I would expect a non-directional hypothesis to be one which leaves it to the reader's imagination tothink about what the end result will be.A directional hypothesis is the opposite, whereby one tries to convince others that his hypothesis iscorrect, instead of letting people judge for themselves.directional implys you are "hypothesising" and predicting the outcome before you conduct yourresearch.None directional implies you don't know which way it will go. Its more hypothetical.2)
hether you frame your alternative hypothesis, H
a
, as one-sided (directional) or two-sided (non-directional) is really up to you, but should be decided before you look at the data. It will affectthe calculation of your p-value and ultimately your conclusions from the test. In most cases therewill be a sound, obvious reason for choosing one or the other.For example, if you were testing the effectiveness of a new anti-cholesterol drug you'd probablyonly be interested in testing whether the average of the experimental group was
lower
than thecontrol group. So H
a
is directional, or one sided. If on the other hand you were testing, forexample, whether a Group A performed better on a test than Group B, your H
a
would be that theaverage of Group A does not equal Group B. That is, you're not sure, before you run the test,
whether Group A should perform better or worse than Group B. So your test is non-directional,or two-sided.
Why researchers choose directional or non-directional hypothesis? Explain briefly?
esearchers choose the directional way of hypothesis because the variables involved in this aredependent and are interlinked and show the effect on one another. using this type the researchers findthe solution of the problem in a systematic way because first variable give the direction for the nextstep. the non-directional type is also used but in this type the variables are just interlinked and notdependent. this also give the reseracher the sufficient information but does not give the researcher thefurther direction they have to find the next step by self. the variables are to be defined by self.Researchers choose the directional or non-directional hypothesis, becausethis can help them to prove the Hypothesis or to find new things. Directionalhypothesis measures the direction of variation of two variables. Thiseffect of one variable on the other variable can be in positive direction orin negative direction. Non-directional hypothesis does not indicate the kindof effects but only shows the relation between two variables.
How do you determine whether you have adirectional or non-directional alternatehypothesis?
Consider the hypothesis as a trial against the null hypothesis. the data is evidence against the mean. youassume the mean is true and try to prove that it is not true.If the question statement asks you to determine if there is a difference between the statistic and a
value, then you have a two tail test, the null hypothesis, for example, would be μ = d vs the alternatehypothesis μ ≠ d
if the question ask to test for an inequality you make sure that your results will be worth while. forexample. say you have a steel bar that will be used in a construction project. if the bar can support aload of 100,000 psi then you'll use the bar, if it cannot then you will not use the bar.
if the null was μ ≥ 100,000 vs the alternate μ < 100,000 then will will have a meaningless test. in this
case if you reject the null hypothesis you will conclude that the alternate hypothesis is true and themean load the bar can support is less than 100,000 psi and you will not be able to use the bar. However,if you fail to reject the null then you will conclude it is plausible the mean is greater than or equal to100,000.