Analytical Chem Lab Report 6 m&m's

Have I missed something?
Anybody notice that Stringfield's spreadsheet appears to have calculated Standard Deviation instead of RSD as labeled?
Manual calls for StdDev.
If it were intended that we calculate RSD, the manual would have said, right?

I glanced over the lab questions earlier and was trying to figure out exactly what he wants. He had said in class that he did not need an Excel sheet, but he wants us to calculate things in an Excel sheet, so I assume he really does want one. It sounds like he wants mean and standard deviation of only 2 colors for each type of candy in part A - both for your own data and the entire class data.
Question 3a is not very clear.
Not sure on Part B or Part C yet either.
What is the point of this lab anyways?

3a. He's getting at how the st deviation should go down with an increase in sample size, because, we are more likely to have a sample that is most like (representative of) the whole.

I think you are right, we better include a spreadsheet. If you click tab E, Mari C of 2005, left a spreadsheet for us to fill in our own data.

Also I think my big bags were 12.6 oz size - not 14, as on the class spreadsheet. Found this on m&m website under nutrition:
Available in these sizes:
1.74 oz., 3.27 oz., 5.3 oz., 8.2 oz., 12.6 oz., 19.2 oz., 42 oz, 56 oz.

In class he told us they wee 12.6 oz, so he probably just did not update his sheets.
I am just wondering how he wants us to answer the questions. Do we need to put all kinds of data in the sheets to support our answers (like for 3b.)?
Also, do we need to cut and paste the entire class data for the 2 colors we pick so that we can calculate the mean and standard deviation.
It looks like he wrote RSD %, but the formula in the sheet is just for standard deviation.
I am kind of stuck on this because I really don't know what he wants.

Lab manual said this was published in the Journal of Chem Education.
found this on the web, may or may not help.
might be good to see what the author intended.
http://www.jce.divched.org/Journal/Issues/2000/Aug/abs1015.html

I really think we will have to take this to the RSD & talk about bell curve & confidence levels.
It's not due until Thursday. We should discuss this in lab tomorrow.

Actually, the textbook has info about sampling methods on p.8.
(I'm hearing Kyle say not to make this too complicated). We will have to back up our statements by referring to our statistical analyses.

I am just going to wait until tomorrow and ask him. I don't want to make this huge spreadsheet and then he says not to. Why do more work than I have to? I think the main issue is that he did not write this manual, so I don't even know if he knows what is in it sometimes!

Wow this one is pretty confusing. It looks like we need to calculate a few things to get to our conclusions, but if we need to reference the calculations does that mean we need to show or present them to him somehow? He said he didn't want an Excel sheet yesterday, but that would be the preferred place to do them. I'm figuring he's really only interested in our answers/conclusions, but I guess it wouldn't hurt to print out the calculations we did from the spreadsheet.

Does anybody have the impression we are to add the 2 colors, of our choosing, and then do the average & mean?
I don't think so, but I'm looking for second opinions. - NO because in 3a, we are to consider each color we selected.
He already gave us class mean & standard deviation under totals for each- no need to recalculate.
I am doing a spreadsheet. Trying to figure what % of what to include.
This pdf gave me some idea of words & how to analyze. http://web2.wku.edu/~charles.henrickson/sample.pdf
Excel has a cool function for viewing 2 different spreadsheets at the same time. View tab, then side by side.

Here's what he told me:

"If there are calculations that were not already done on the Excel
sheet I posted, then you should show the final answers to those
calculations in the word document you will print out and turn in. You
can do those calculations in Excel and then export the spreadsheet
into Word if you wish. Import the spreadsheet as part of your answer
to that particular question.

If the needed calculations were already done in the posted Excel
sheet, then just reference them by worksheet name (part A, part B,
part C) and Row/Column number.

Hope that helps.

Tom"

So we WILL need to give him some sort of printout of our calculated results, so hang onto them.

Thanks, Kyle, that does help. Makes sense that we calculate & include those sections called "Totals."
We DO have to tabulate the RSD & mean for each color for the whole class. NOW I see it.

Is there a mathematical reason why we should tabulate RSD, rather than Standard Deviation, when we fill in the blanks on Excel?
First, I thought there was a mistake on the spreadsheet label of RSD. I'm having second thoughts. Anybody have discussion?

I agree, this lab does seem some what pointless. It would have been ALOT better if it was closer to where we were doing the statistics calculations instead of in the middle of titration stuff. Oh well. I just found the mean and standard deviation for everything. Better to give him too much than not enough. He can sort through it himself..... so...... Whats up?


Shauna J

Why does Excel do this? (2/3) x 100% = 70%
2 is standard deviation, and 3 is mean
It just makes no sense to make things even worse than they really are.
It's wrong to use the StDev function?
Have to use =STDEVP. Now the RSD is 62.3%. I get it.

I don't know what is going on there..... but you can use stdev function and it will give you the right standard deviation, but in some cells he already had it formatted for percent, so its gonna multiple an extra 100 on there.... don't know if that helps you. Also, we are calculating the relative standard deviation so we can compare our values to one another. its still standard deviation.... just relative.... to what we're doing.......


Shauna J

If you say so. This is the same argument I had with Excel that cost me several hours of trying to figure out what was wrong with Excel. It also cost me being able to throw out an outlier before. I assume EVERYBODY is using stdev formula.

Where the FUCK is the class calculations for part C numero 2. There's no section for it, and I sure as hell am not about to calculate the total for EACH type of bag that every person had. This lab absolutely blows, and I don't even like M&M’s.

you know, didn't even notice that there wasnt anything there..... oh well, i didn't do anything with it and i'm not going to. my report is done and that is how its going to stay!.... they used to have m&ms that had chocolate and like rice krispie type things in it.... i loved those.... they took them away..... they suck!



Shauna J

For Part C all I did was use data from the other people who had the same bag as me. I just added the means for each person and divided by 3 (there were 3 people with Bag #1). I really don't know if I did any of this lab right, but I finished it earlier today and I am off to bed now. I will not even look at it again!

LOL. I don't like m&m's any more & I'm real tired of seeing Jason's name.
Couldn't get paste special to work. Finally got parts of Part A hidden.
It pastes into Word rather poorly.
I'm thinking of being an art major.