Data Dive 3.3

Does carbon dioxide help us find planets?

Two things can rise together without one causing the other.

You will need paper and a pencil, and a browser for step 3

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Step 1 of 5 · Your guess

What do you think?

Scientists measure how closely two things move together with a score called r. It runs from 0, no connection, to 1, moving in perfect step.

Here are two pairs, from 1992 to 2025. Carbon dioxide in the air and Earth's temperature: r = 0.937. Carbon dioxide in the air and the number of planets found around other stars: r = 0.918.

Write it down before you lookBoth scores are high. Which pair do you think is really connected? Write it down, and why.
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Step 2 of 5 · Look

Carbon dioxide and Earth's temperature

CO2 against global temperature, 1992-2025r = 0.937 - NOAA Mauna Loa and NASA GISTEMPtemperature anomaly, degrees CCO2, parts per millionone year0.220.4850.751.0151.28356.54374.243391.945409.648427.35

1992 to 2025. The planets chart is waiting for you in the pool.

How to read it. Each dot is one year. How far right it sits is the carbon dioxide that year. How high it sits is how warm Earth was.

Find out
  1. Do the dots make a line? Which way does it go?
  2. The planets pair has almost the same score. What do you think its chart will look like?
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Step 3 of 5 · Try it

Now you try it, on the same data

This opens the pool, the site's chart tool. The words in bold below are buttons and menus you will see on the screen.

Do these five things

Open the pool on this file: data.sfhsbta.com/thepool?file=correlation_co2_temperature_exoplanets.csv&mark=point

  1. Under across, pick co2_ppm. Under up, pick global_temp_anomaly_c. Hover the first and last dots and read both ends.
  2. Under up, pick exoplanets_discovered_cumulative. Hover the ends again. Is this cloud any less straight?
  3. What do both charts have in common on the across side?
  4. Write three other things that went up between 1992 and 2025. Would they make the same kind of chart?
  5. Write one thing the r score can tell you, and one thing it cannot.
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Step 4 of 5 · Say it

Your answer, in one sentence

I think the carbon dioxide and planets pair <is or is not really connected> because <what the chart shows> and I checked it by <what you did to the chart>.

The last part matters most. It shows you did not just look at the chart, you tested it.

Here is one exampleI think the carbon dioxide and planets pair is not really connected, because both just went up over the same years. I checked by putting planets on the side, and the cloud was just as straight as the temperature one, so a straight line was never proof.
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Step 5 of 5 · What you found

Check your numbers

2 to 6091
planets found around other stars, 1992 to 2025
356.54 to 427.35
carbon dioxide in parts per million, the same years
The big idea: moving together is not causingWhen two things rise together, their r score will be high. That does not mean one causes the other. Lots of things went up since 1992. To show a cause you need a reason, like the science of how carbon dioxide traps heat, not just a straight line.
One more thing to think aboutSomeone shows you a high r score for something you already believe. What should you ask them for?
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After the dive

The charts you used today

the scatter

Each dot is one thing measured twice. A tight cloud along a line means the two move together.

What it leaves outTwo things moving together is not one causing the other, and a third thing neither axis shows may be moving both.

library · ladder · dives · the pool · this dive’s worksheet

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