Linked Questions

14
votes
4answers
21k views

How to specify the null hypothesis in hypothesis testing

What is a good rule of thumb for how to choose the question for the null hypothesis. For instance, if I want to check if the hypothesis B is true, should I use B as the null, B as the alternative ...
18
votes
6answers
5k views

Why is statistics useful when many things that matter are one shot things?

I don't know if it's just me, but I am very skeptical of statistics in general. I can understand it in dice games, poker games, etc. Very small, simple, mostly self-contained repeated games are fine....
16
votes
4answers
6k views

Misunderstanding a P-value?

So I've been reading a lot about how to correctly interpret a P-value, and from what I've read, the p-value says NOTHING about the probability that the null hypothesis is true or false. However, when ...
9
votes
8answers
426 views

Should I trust the $p$-value in statistical tests?

I got into a debate with my supervisor over a recent paper. The test of correlation in a sample of 77 participants yielded a p-value smaller than 0.05. After removing a few participants (because later ...
31
votes
3answers
868 views

Accommodating entrenched views of p-values

Sometimes in reports I include a disclaimer about the p-values and other inferential statistics I've provided. I say that since the sample wasn't random, then such statistics would not strictly apply....
18
votes
6answers
670 views

How to explain hypothesis testing for teenagers in less than 10 minutes?

For over a year now I've been giving a one-hour "a taste for statistics" class. Each time I get a different group of kids coming over, and I give them the class. The theme of the class is that we run ...
11
votes
3answers
1k views

“Reversed” Shapiro–Wilk

The Sharipo-Wilk test, according to wikipedia, tests the null-hypothesis ($H_0$) "The population is normally distributed". I am looking for a similar normality test with $H_0$ "The population is not ...
4
votes
2answers
782 views

What is this equation (pictured) called?

Could someone provide some Google-able words for this equation? $$Q_{\chi^2,d} = \left[2^{d/2}\Gamma\left(\frac{d}{2}\right)\right]^{-1}\int_{\chi^2}^\infty (t)^{\frac{d}{2}-1}e^{-\frac{t}{2}}dt$$ ...
5
votes
2answers
31k views

Why does the p-value double when using two-tailed test compared to one-tailed one? [duplicate]

Since this has been marked as a duplicate, I want to clarify that it's not about critical values of one- vs two-tailed tests, but the calculation of the p-Value in this case. I get that in a two-...
3
votes
2answers
23k views

P-value vs Type 1 Error [duplicate]

I am trying to understand the relationship of a p-value vs Type 1 error rate. My understanding of one interpretation of a p-value is the following: "the p-value tells us the probability of making a ...
3
votes
2answers
5k views

Is “Confidence Level” just 1 minus P-Value?

If the results of a Chi-Square test give a P-Value of 0.01 then can we say that the confidence level in their being a difference is (1-0.01) = 99% confidence. Background. We are conducting website ...
2
votes
3answers
16k views

Pearson correlation coefficient test: low $r$ and low p-value

I am running a correlation coefficient test, and the results were: $r = 0.382, p = 2.76 \times 10^{-13}$. So the $r$ value is not that impressive (usually we see $r>.5$), but the $p$-value is ...
2
votes
2answers
18k views

Confused about region of rejection vs P-value.

What exactly is the difference between the Region of Rejection and P-value, when doing Hypothesis Testing? Read this online: To find a rejection region, work backwards from the level of ...
9
votes
1answer
5k views

How to test the median of a population?

I have a sample of 250 units. The distribution is asymmetric. I want to test a hypothesis that the median of the population is different from 3.5, so I think a one-sample test would be appropriate. I ...
3
votes
1answer
979 views

Chi-square test statistic is significant but $p$-value says otherwise - what's the correct interpretation?

I have obtained a Pearson's Chi-Square test statistic value of $0.065$, for $1$ df, and a $p$-value of $0.799$. Comparing my calculated $\chi^2$ test statistic with the critical value in the $\chi^2$...

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