Experimental Design


I am not sure whether my experimental design right. Can you suggest me something? and also how many treatments do I have?

* all the information is in attached file


TS Contributor
Looks OK to me. I would say that you have 28 possible treatment combinations:

4 loudness levels x 7 music types = 28
plus 1 control = 29

Make sure that the treatments are done in random order - that way you minimize any "fatigue" factors that may occur if the participants have to re-write a lot of text passages (will each participant be exposed to all 29 possible treatments?)


Thank you very much for your help.
I have several questions: What is the name of my experimental design?I can't understand it, because it has 2 factors, blocking and matched pairs design at the same time...
And also last time you wrote me that I have 29 treatments. But I still think that I have 28 treatments, because control of the experiment is included in one of the levels of the background music condition : no background music.
And to answer your question, each student will be assigned to 7 treatments.
I attached a new version of the experiment. Can you please read it and suggest me something?

Thans a lot! :rolleyes:
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TS Contributor

Thanks for the clarifications - makes more sense now. Your design doesn't necessarily need to have a "name" taken from a neatly-defined category in a textbook. You could call it a two-factor factorial with a blocking factor.....

factor A: music type
factor B: loudness
blocking: gender

A couple of things:

-I think it's more important to make sure that the loudness levels are presented to the participants in random order, rather than randomizing the order of music types (fatigue would have more of an impact with increased loudness, in my opinion)

-Also - this is critical (and required) whenever you have a study involving human subjects:

(1) each participant must sign a form stating that they are willingly participating and they understand the purpose of the study - since they are only in 9th or 10th grade, you may want to get parental permission as well
(2) the form should state that they can back out of the study at any time without any "retribution" or "penalty" - i.e., the loudness level of the music may get uncomfortable, and may even be loud enough to cause harm if one's hearing is sensitive
(3) they need to know, ahead of time, how "loud" the music may get so that they can make a good decision about participating

Good luck.
Design 3


Thank you very much for your suggestions!
The only thing I don't understand is that why loudness should be randomized. One student will be assigned only to one level of loudness and 7 different levels of background music condition. So only seven treatments, and I think that it does not matter in what order loudness will be, since different levels are assigned to different students (hope you understood me:p )
I am a 10th grader and this is my ScienceFair project, so all "experimental subjects" are my classmates. My teacher handled me this form to sign, but do I still need agreement from their parents?
If you have any suggestions, please write.

Thank you sincerely.


TS Contributor
OK - I understand it now. Sounds good. Since they're your classmates and your teacher is sort of handling the forms, then it probably isn't necessary to get parental permission.

However - the participants should still get to hear how loud it will get before they agree to participate - and make sure they're able to "back out" whenever they want.

Sounds like a very interesting project - best of luck!

Let us know how it goes.