Science Buddies: "Ask an Expert"

Need help with music effects on power kicks in taekwondo. I plan on having martial art students kick a kick bag 5 times. I will video tape the kicks. I have designed a poster with inches on it. I will record how far each kick moved the bag by viewing the tape on slow motion. Then, the student will put on music and do the same five kicks. Again I will measure and compare the results. I must convert inches to mm. I will also ask the student if they feel the music made their kicks more powerful. Does this sound like a good project? Any suggestions. No $ for a speed camera.

Hi,

I think this sounds like a great project! I do have a few suggestions, though. First of all, kicks are probably going to vary a lot, both from person to person and even within an individual person. So, I would suggest having a sample size of at least 5-10 people and doing at least 10 kicks per treatment (music/no music).

'Music' is pretty broad--you might consider investigating different types of music to see if they have different effects, or even testing music the person likes vs. music they don't like.

Another thing to consider is that people may get tired as they do more and more kicks--so you should probably vary whether people start with music or without music. That way, you can make sure that if you do see a difference, it's not just due to people getting tired.

Finally, you will need to work with your camera so that you're sure you can measure what you need to measure. I suggest doing a bunch of trial runs where you take some video and then play it back and see if you can see how much the bag moved. It should be possible if you focus on the ruler rather than on the bag itself.

Good luck!

Hi,

Melissa has given you some very good advice. I would especially stress the order of the treatments (music/no music). Because subjects may get more tired as they kick more times, have half of your subjects start with music, then switch to no music, and have the other half start without music, then switch to music. This is a very important method of reducing any noise caused by exhaustion level on the part of the subjects. Also, be careful to only compare kick strength between the same person since, as Melissa has pointed out, kicks vary between people. Feel free to ask if you need statistics help on this also.

Hope this helps!
Aaron

Dear science Buddies,
I have received my pre-abstract and reference paper on the effects of pop music on taekwondo side kicks. After submitting a couple of times, I have received an A and also another A on my reference list. I will hand in my research paper this week and must begin on my data chart. ddddddAny help on staftistics would be helpful. I have tested 25 taekwodo students. Five kicks without music (control) and 5 kicks with music (manipulated. I have measured how far a 90lb. kick bag is moved in centermeters as ;measured on a chart I have placed behind the kick bag . I have recorded o a camcorder and played back in slow motion for the results. I am now averaging the 5 kicks without music and 5 kicks with music for each participat. The I will take all the averages of the control group and average into one number. I will do the same thing for the music manipulated group. I should be able to see if there is a significant difference between the two groups. Any suggestios????

Hi. What an interesting project! Since I enjoy listening to music while working out, I would be very interested in the results.

Have you defined your null hypothesis? Would you mind sharing?

As far as your data analysis goes, there is an extensive process to determine whether a significant difference between two groups exist. However, that is well beyond middle school math. So, I believe reporting averages for the two groups will do fine. Do you have a number in mind to determine whether there is a difference in distance measured to conclude that kicks are more powerful with or without music (ie, there is a significant difference between the groups)? Meaning, if the difference in distance between the two groups is 5 cm, there is no difference; but you will call it significantly different if the difference between two groups is 6 cm or greater? For Tae Kwon Do, is there a definition of "powerful kick" you can use to determine this number?

I recommend taking only two averages and comparing the two to determine significant difference:
1. All the results from all students for no music
2. All the results from all students for music

I don't recommend taking an average for each student, and then taking an average of those averages. This only increases your error in your results. In more advanced statistical methods, looking at the variability within each student is certainly critical to examine. However, that is well beyond middle school math. I wouldn't worry about it. I would certainly check out these two webpages that discuss how to summarize your data. Besides reporting average, reporting the range of kick distance for both groups would also be useful information.
https://www.sciencebuddies.org/science- ... ysis.shtml
https://www.sciencebuddies.org/science- ... data.shtml

Certainly write back if you have any further questions. Good luck!

I have a few question: 1. I have recorded the kicks on a chart behind a 90lb kickbag. I had to record in inches to see on my camcorder. For my spreadsheet, I need to record in centimeters. To convert the inches into cm. may I just us a centimeter ruler? I know the formula 2.54, but it seems unnecessary if I can just drop the 0 in mm. Centimeters are indicated on the inch rulker also.
2. I need to cdreate an xy graph. The y would be power kicks with music. Not sure if the y would be the participants? Should this be a bar gragh comparing the controlled group (without music) and the group with music? I have never used graphs in excel, I hope it is not taoo difficullt.
Thanks
If I listen to pop music, then my taekwondo side kicks will be stronger as measured by the movement of a 90lb kick bag.

Hello!

This project sounds very interesting, and I'm excited to learn of the results. To answer your first question, you want to multiply the number of inches by 2.54 to determine how many centimeters that the bag travelled. Here is a nice online tool that does the conversion for you: http://www.convertunits.com/from/inches/to/cm

I think that you should consider creating one xy graph with the y axis representing the distance that the bag moved and the x axis representing the participant. After averaging the distances of the 5 kicks, you should create 2 bars per participant (perhaps color code them), with one representing the average distance kicked with music, and the other representing the average distance kicked without music. This way, you can compare on a participant by participant basis, how the addition of music affecting the distance that the bag was kicked.
Here is a site that explains the basic of dependant and independent variables (which will help you understand what values go on the x and y axis): nces.ed.gov/nceskids/help/user_guide/gr ... iables.asp
Here is a site that explains bar graphs with Excel: http://www.ncsu.edu/labwrite/res/gt/gt-bar-home.html
Check out the section that explains the graph of two independant variables.

Hope this helps, Good Luck with your project!
Nithin T

I have completed my project. It seems pretty good. The difference of the total average the 90lb kick bag was moved without music was 25cm, The totla disstance it was moved with music was 33cm. There was a 8cm difference. I arbitraryily selected a standard diviation of <5 and >5cm. The experimebnt provedmore than >5cm with music. What is the standard diviation? How do I come up with this? Please help

Congratulations on finishing your data collection! Sounds like you found some interesting results.

You say you selected a STANDARD DEVIATION of <5 and >5 cm. Are you trying to say you will conclude that music makes a difference if the measurements are greater than 5 cm (which in your case, it is)? If so, then 5 cm is your EFFECT SIZE. So, if the difference was less than 5 cm, you would not consider there to be a difference between music and no music. Be prepared to explain why you chose 5 cm. Why not 3 cm, 7 cm, 10 cm? There is no right or no wrong answer to this question, as long as you can come up with an explanation.

Let's talk about what numbers you need to report. You will need to report numbers that describe central tendency and dispersion of your data, and you are well on your way in doing this. The mean will describe your central tendency. The standard deviation is one way to describe dispersion of your data. Range (lowest value to highest value) is another way to describe dispersion.

The standard deviation is a useful piece of information. Below is a good website that describes it in very simple terms with an easy to follow example and how to calculate:
http://www.mathsisfun.com/data/standard-deviation.html

Just be sure you understand what standard deviation means and what it tells you about your data. 68% of your data (centered on your mean) falls within 1 standard deviation. 96% of your data (centered on your mean) falls within 2 standard deviations. 99% of your data (centered on your mean) falls within 3 standard deviations. So, in looking at the range (mean minus 2 standard deviations) to (mean plus 2 standard deviations), you have a good snapshot of kick performance over the entire population (and not just your data sample).

What I have just described to you is well beyond middle school math. I commend you on wanting to include this information in your report, because it is useful information. However, you must be prepared to be able to explain the calculations you include in your report. If you don't feel comfortable describing the standard deviation, simply include range for each group (music and no music). Also, certainly feel free to write back with any further questions about standard deviation or any other problems you are having.

I hope this helps. Good luck!

Thanks for the help on SD and other data. I will try to explain range. I hope I can do this on excell or something easy. Any suggestions? This is a project dear to my heart, however, it's been a n eighth month project. I don't think it will ever be through. Oral Presentation will be next week. Judging on the 4th of Feb. Starting to panic.

Hello,

Excel does support some basic statistical analysis, including standard deviation and mean. Here is a link that explains the process: http://www.gifted.uconn.edu/siegle/rese ... dexcel.htm

Good luck on your report, I'm sure you will do great.
Nithin T

An excellent website Nithin has provided. I'm sure you will do well this week with your presentation. Let us know how it goes. Good luck!

Thank you agai for all the help. I did a practice run in my class. My friends said I did well. This Friday is the judging. I feel confident but will study for the next three nights!

Good luck! Let us know how it goes.

Excited to report I won first place with my project. Now I have regionals in several weeks. Thank you again for all your help Science Buddies!

Congratulations! You certainly worked hard and thought the project through. Good luck at regionals. If there were suggestions from the science fair you are having problems with, certainly write back.