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How Scientists Count Farts

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Name Date

Watch

  1. I’m farting for science!youtube.com/shorts/8OqwMEsxD38

Word of the day

Flatus (FLAY-tus). Gas produced in the intestines, partly by bacterial fermentation of undigested food, and passed through the anus.

Word partComes fromMeaning
fla-Latin flāreto blow
-tusLatin -tusthe act of
  • Flatulent comes from New Latin flātulentus, formed from flātus.
  • Italian fiato, “breath,” comes from Latin flātus, and Italian also uses the word for a wind instrument.

Bonus word. Microbiome (from micro-, “small,” bio-, “life,” and -ome, as in biome) names the microorganisms in or on a body or in an environment, together with their genetic material. American molecular biologist Joshua Lederberg coined the word in 2001.

Predict

  1. Australian researchers asked 6,416 people to log each fart in a phone app, as close as possible to the moment it happened, on at least 3 days. Make a guess before you read the paper. How many farts a day do you think the average participant logged? Give your reason in one sentence.

    Hint. In the video, Raven gives an old estimate of 10 to 14 a day and a sensor estimate about three times higher. Would counts that people tap into an app come out closer to the old estimate or to the sensor estimate?

Read the paper

Brindal and Baird, “Regular Flatulence Patterns Among Community-Dwelling Individuals in Australia,” JAMA Network Open, 2026. The paper is free to read.

Emily Brindal and Danielle Baird of Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) created a phone app called Chart Your Fart. From November 2024 to February 2025, 6,416 participants aged 14 and older logged 360,192 farts, each as close as possible to the moment it happened, for a mean of 10 days. The table below comes from the paper’s Table. It compares who joined with Australia’s population aged 14 and older, and it gives the farts logged per day. It leaves out the 146 participants in the paper’s Other gender group, which has no population figure.

GroupShare of sample, %Share of Australian population, %Sample minus population, percentage pointsFarts logged per day, mean (SD)Farts logged per day, median (IQR)
All participants1001005.0 (3.8)3.8 (2.5 to 6.2)
Female50.750.74.8 (3.6)3.8 (2.4 to 6.0)
Male47.049.35.2 (3.9)4.0 (2.5 to 6.5)
Age 14 to 2513.317.74.4 (3.4)3.3 (2.2 to 5.3)
Age 26 to 4538.133.95.2 (3.8)4.0 (2.6 to 6.5)
Age 46 to 6538.729.25.0 (3.9)4.0 (2.5 to 6.3)
Age 66 and older10.019.24.8 (3.7)3.7 (2.4 to 5.8)

  1. Quantitative reasoning Fill in the blank column of the table. Which age group did the Chart Your Fart study oversample the most? Which did it undersample the most? Would weighting the age groups to match Australia’s population move the mean of 5.0 farts a day by much?

    Hint. A positive difference means a group made up more of the sample than of the population. Compare each age group’s mean with 5.0.

  2. Process of science The Chart Your Fart app couldn’t tell a day with no farts apart from a day the participant forgot to log, and participants had no way to report a day with zero farts. If some participants had days with zero farts, how would leaving those days out change the Chart Your Fart study’s mean?

    Circle one. Make the mean too high / Make the mean too low / No change

    Hint. An average of only the days with farts leaves out the zeros.

  3. Pathways and transformations of energy and matter The paper’s Figure shows logging rose through the day and peaked between 6 and 10 pm, a pattern that overlaps with when Australians eat the most food energy and fiber. What mechanism could link the evening peak in logged farts to food eaten earlier in the day? What besides gut chemistry could produce the same pattern?

    Hint. Fiber passes the small intestine undigested. Then think about when people are free to log.

  4. Process of science The app participants logged a mean of 5.0 farts a day. The Smart Underwear study, which used a hydrogen sensor, found a mean of 32. How many times larger is 32 than 5.0? How would you design a study to measure how many farts a self-report app misses?

    Hint. Have the same people use both methods at the same time.

Exit ticket

Brindal and Baird’s table summarizes 360,192 farts logged by 6,416 people. What does the Brindal and Baird table show about how often people log farts? What’s one question the table can’t answer?

Hint. Start with the mean and the median. Then think about the farts a person can’t log.

Sources