Science Buddies: "Ask an Expert"

This is my project. I am finding that smokers can hold their breath longer than non-smokers. That was NOT my hypothesis. Could this be true???

Hi, this is a very interesting project! It's highly unlikely that smokers would have a greater lung-capacity than non-smokers because smoking decreases the amount of oxygen absorbed per breath. Have you controlled for how long the participants have been smoking? Also, you may need a larger sample size. In general, 30 is the magic sample size for this kind of experiment, meaning 30 participants per group.

Here is a link to a previous post about smoking studies: viewtopic.php?t=4708

I hope this helps!
Jen

I have 25 smokers/non-smokers per group. The results for the smokers time are definitely higher. I read on-line that smokers can hold their breath longer because they are used to having less oxygen. I think if his activity required some type of exertion then the results would be different. They are just sitting and holding their breath. I am at a loss. I am just looking for something that says this could be possible.

Hmm, definitely a strange result! All of the published studies I've been able to find indicate that your hypothesis is correct- smokers cannot hold their breath as long as non-smokers.

Like jcschrandt said, small sample size is a good way to explain this conflicting result. Another possibility is the method used to measure how long each subject could hold their breath. I think a professional academic study would typically use a device that requires each person to blow into it and sustain this breath as long as possible (see https://www.researchgate.net/publicatio ... ot_workers "Breath-holding time was recorded using the mouth piece attached to the mercury manometer where the subjects were advised to blow through the mouth piece after full inspiration as long as possible till the breaking point following standard methods and precautions").

Holding one's breath is a bit different from exhaling as long as possible. It seems reasonable that reduced lung capacity may be easier to detect using the exhalation method. Plus, if the explanation that smokers are accustomed to having less oxygen is true, then I could definitely see these two methods leading to different results.

Something else you could do is try a "student's t test" to see if your results are statistically significant. That's a lot to explain here, so just try Googling it until you find a nice explanation, or check out this video starting around 1:00 (http://study.com/academy/lesson/what-ar ... roups.html)

Good luck!

Something else to consider, is that smokers practice taking deeper breaths as they smoke than the average person is used to in normal breathing. Professional vocalists and some athletes learn how to take full deep breaths. You might also try those breath measuring devices they use in hospitals to determine how deeply the study subjects are inhaling.