Linked Questions

59
votes
13answers
16k views

If we fail to reject the null hypothesis in a large study, isn't it evidence for the null?

A basic limitation of null hypothesis significance testing is that it does not allow a researcher to gather evidence in favor of the null (Source) I see this claim repeated in multiple places, but I ...
0
votes
0answers
36 views

Interpreting hypothesis testing result (assuming that the null hypothesis is true) [duplicate]

I have a doubt on how to interpret a result of a hypothesis test. For example, a scenario where I have an existing configuration and also a new configuration. I am trying to check if with the new ...
0
votes
1answer
26 views

hypotheses testing [duplicate]

so I'm new to statistics and am not very comfortable with it yet. It may be a very simple question, but I'm finding this very difficult to understand In research papers the hypotheses are mostly in a ...
35
votes
7answers
6k views

Why is the null hypothesis often sought to be rejected?

I hope I am making sense with the title. Often, the null hypothesis is formed with the intention of rejecting it. Is there a reason for this, or is it just a convention?
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
6answers
2k views

Using p-value to compute the probability of hypothesis being true; what else is needed?

Question: One common misunderstanding of p-values is that they represent the probability of the null hypothesis being true. I know that's not correct and I know that p-values only represent the ...
3
votes
3answers
10k views

Chi-Square-Test: Why is the chi-squared test a one-tailed test? [duplicate]

In my Masters thesis I conducted an experiment in that subjects should decide between two alternatives. I had a control and a treatment group. The hypothesis was that in the treatment group more ...
11
votes
2answers
1k views

Family-wise error boundary: Does re-using data sets on different studies of independent questions lead to multiple testing problems?

If a team of researchers perform multiple (hypothesis) tests on a given data set, there is a volume of literature asserting that they should use some form of correction for multiple testing (...
7
votes
3answers
3k views

Is there a consensus on adjusting alpha for multiple contrasts if the main effect is significant?

After talking to a couple of statisticians, reading some book sections, internet articles, and forums like this, I am still unclear about multiplicity adjustments of post hoc tests and contrasts. Let'...
12
votes
1answer
4k views

Goodness-of-fit test in Logistic regression; which 'fit' do we want to test?

I am referring to the question and its answers: How to compare (probability) predictive ability of models developed from logistic regression? by @Clark Chong and answers/comments by @Frank Harrell. ...
4
votes
2answers
8k views

How to set the significance level in a hypothesis test correctly

I have difficulties understanding probabilities. Let's imagine I have a test based on time series regressions and my null hypothesis is that I will pass my next exam in statistics. The test is ...
1
vote
2answers
7k views

How to interpret MCAR (missing completely at random) any papers that I can read?

When dealing with missing data and Little's missing completely at random test, it's widely considered that if the test has a significance level of P>0.05 the data can be considered as MCAR. But, I ...
7
votes
2answers
848 views

Is there a multiple testing problem when performing t-tests for multiple coeffcients in linear regression?

This question comes from a discussion on the recent post by @rvl It's all in the family; but do we include the in-laws too? Here's a common scenario that I've seen many times. A researcher runs a ...
2
votes
1answer
5k views

Test if two normally distributed random variables have the same mean

We have two independent random variables which follow normal distributions $X_1\sim \mathcal N(\mu_1,\sigma_1)$, $X_2\sim \mathcal N(\mu_2,\sigma_2)$. From the context, we have that $\mu_1\leq\mu_2$. ...
4
votes
4answers
661 views

When a one-tailed test passes but a two-tailed test does not

(Sorry if this is obvious or is a duplicate. I couldn't find one.) Suppose two researchers are studying whether average height of some population has changed significantly. Researcher 1 hypothesizes ...

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