2652: Proxy Variable

2022-07-30T18:51:59Z

Ena9219:

{{comic
| number = 2652
| date = July 29, 2022
| title = Proxy Variable
| image = proxy_variable.png
| titletext = Our work has produced great answers. Now someone just needs to figure out which questions they go with.
}}

__NOTOC__

==Explanation==
{{incomplete|Created by a PROXY BOT IN NO WAY RELATED WITH THE ORIGINAL BOT, SO MARRIAGE WOULD BE ETHICALLY AND LEGALLY ACCEPTABLE - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

In this comic, [[Hairy]] is discussing use of a proxy variable with [[Cueball]]. In statistics, a {{w|proxy variable}} is used as a stand-in for one or more other variables that are difficult to measure. In order to be useful as such, proxy variables must be correlated with what they are intended to represent. For example, a drug might aim to reduce deaths from a slow-acting disease. But testing if it reduces deaths might take many years, so researchers might test for a proxy outcome instead, like whether it does not result in loss of bone density or damage to cells.

Hairy is dismissing the question of whether they are studying the right variable as too expensive to answer. This is deeply ironic and thus satirical, because good {{w|experiment design}} requires sufficient attention to the robustness of all the involved parts of an experiment, even if the expense may be prohibitive.

Choosing the wrong proxy variable might make the research misleading, irrelevant, or as the title text suggests, answer the wrong question. Separating correlation from {{w|Causality|causation}} is necessary when interpreting proxy variable results to make sure the question they answer is known. Mere correlation instead of {{w|Causal analysis|authentic causation}} yields weaker results. {{w|Exploratory causal analysis}} can assist with finding useful proxy variables, but is difficult for the layperson to interpret, and can be misleading.

The title text's notion of having an answer without knowing the actual question could be be a reference to the classic comedy science fiction novel {{w|The Hitchhiker's Guide to the Galaxy|The Hitchhiker's Guide to the Galaxy}}, where in one scene Earth turns out to be a supercomputer built for the purpose of figuring out the question for the answer "42."

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Hairy uses a pointer to show Cueball a poster of a line chart above a candlestick chart. The drawing appears to show a time series with a question mark for future extrapolation, and a box-and-whiskers plot comparing two variables.]
:Hairy: We want to study this variable, but it's too hard to observe.

:[Cut the panel in half so you can only see Hairy and the poster.]
:Hairy: So we're studying this proxy variable.

:[Cueball and Hairy are standing with the poster out of frame.]
:Cueball: Is it correlated with the other variable?
:Hairy: Look, we don't have the funding to answer every little question.

{{comic discussion}}

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2652: Proxy Variable