How to find null hypothesis in an article

In our example concerning the mean grade point average, suppose we take a random sample of n = 15 students majoring in mathematics. Since n = 15, our test statistic t* has n - 1 = 14 degrees of freedom. Also, suppose we set our significance level α at 0.05, so that we have only a 5% chance of making a Type I error.

This is the critical value that we need if we want to reject the null hypothesis.

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How to find null hypothesis in an article

2. If p is greater than alpha, the fail to reject the null hypothesis.

Example: An advertiser claims there is a difference in the median householdincome for card holders of Visa Gold and Gold Master Card. The result of a random sampleof 100 customers from each card group are shown below:


failing to reject the null hypothesis when it is false.

DEVELOPING HYPOTHESES & RESEARCH QUESTIONS Introduction Processes involved before formulating the hypotheses. Definition Nature of Hypothesis

failing to reject the null hypothesis when it is true.

DEVELOPING HYPOTHESES & RESEARCH QUESTIONS Introduction Processes involved before formulating the hypotheses. Definition Nature of Hypothesis

rejecting the null hypothesis when it is true.

Whilst there is relatively little justification why a significance level of 0.05 is used rather than 0.01 or 0.10, for example, it is widely used in academic research. However, if you want to be particularly confident in your results, you can set a more stringent level of 0.01 (a 1% chance or less; 1 in 100 chance or less).

rejecting the null hypothesis when it is false.

So, you might get a p-value such as 0.03 (i.e., p = .03). This means that there is a 3% chance of finding a difference as large as (or larger than) the one in your study given that the null hypothesis is true. However, you want to know whether this is "statistically significant". Typically, if there was a 5% or less chance (5 times in 100 or less) that the difference in the mean exam performance between the two teaching methods (or whatever statistic you are using) is as different as observed given the null hypothesis is true, you would reject the null hypothesis and accept the alternative hypothesis. Alternately, if the chance was greater than 5% (5 times in 100 or more), you would fail to reject the null hypothesis and would not accept the alternative hypothesis. As such, in this example where p = .03, we would reject the null hypothesis and accept the alternative hypothesis. We reject it because at a significance level of 0.03 (i.e., less than a 5% chance), the result we obtained could happen too frequently for us to be confident that it was the two teaching methods that had an effect on exam performance.

rejecting the null hypothesis when the alternative is true.

When considering whether we reject the null hypothesis and accept the alternative hypothesis, we need to consider the direction of the alternative hypothesis statement. For example, the alternative hypothesis that was stated earlier is: