892: Null Hypothesis

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Null Hypothesis

Title text: Hell, my eighth grade science class managed to conclusively reject it just based on a classroom experiment. It's pretty sad to hear about million-dollar research teams who can't even manage that.

Explanation

This comic is based on a misunderstanding. The null hypothesis is the hypothesis in a statistical analysis that indicates, essentially, the "status quo." For example, the null hypothesis for a study about cell phones and cancer risk might be "Cell phones have no effect on cancer risk." The alternative hypothesis, by contrast, is the one we want to prove or disprove - in this case, probably "Cell phones increase cancer risk."

After conducting a study, we can then make a judgment based on our data. There are statistical models for measuring the probability that a certain result occurred by random chance, even though in reality there is no correlation. If this probability is low enough (usually meaning it's below a certain threshold we set when we design the experiment, such as 5% or 1%), we reject the null hypothesis, in this case saying that cell phones do increase cancer risk. Otherwise, we fail to reject the null hypothesis, as we have insufficient evidence to conclusively state that cell phones increase cancer risk. This is how almost all scientific experiments, from high school biology classes to CERN, draw their conclusions.

It is very important to note that a null hypothesis is a specific statement relative to the current study. In mathematics, we often see terms such as "the Riemann hypothesis" or "the continuum hypothesis" that refer to universal statements, but a null hypothesis depends on context. There is no "the null hypothesis." It refers to a method of statistical analysis, not a specific hypothesis. Given that, Megan's response would probably be to facepalm.

Transcript

[A student works at a desk.]

Cueball: I can't believe schools are still teaching kids about the null hypothesis.

Cueball: I remember reading a big study that conclusively disproved it YEARS ago.

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Discussion

If you get a 50% discount at two shops and buy stuff from both of them, you have a 100% discount. Math. That's how it works, bitches. Davidy²²[talk] 10:05, 9 March 2013 (UTC)