## Experimental Design B/C

Jim_R
Posts: 283
Joined: May 13th, 2001, 4:22 pm
Location: Pittsburgh, Pa
Contact:

### Experimental Design B/C

-The path of the Administrator is beset on all sides by the inequities of the selfish and the tyranny of evil men.

-Nothing\'s gonna get deleted. We\'re gonna be like three little Fonzies here. And what\'s Fonzie like? Come on, what\'s Fonzie like?
-Cool?
-Correctamundo. And that\'s what we\'re gonna be. We\'re gonna be cool. Now, I\'m gonna count to three, and when I count three, you let go of your mouse, and back away from the keyboard. But when you do it, you do it cool. Ready? One... two... three.

HeavyHitter406
Member
Posts: 45
Joined: April 13th, 2014, 5:50 pm
Division: C
State: IL

### Re: Experimental Design B/C

I'm new to division C...how do you do Standard of Deviation? That is part of the Statistics in C, right?
2014 (Wright State/Lisle/Grayslake/Regionals/State/Nationals)

Water Quality: 8/1/2/1/2/3
Experimental Design: 12/1/5/5/8/37
Wheeled Vehicle: 32/6/6/2/11/5

actionpotential
Member
Posts: 12
Joined: September 25th, 2014, 5:15 pm
Division: C
State: -

### Re: Experimental Design B/C

Hey Heavyhitter!

So I've always been confused by that big complicated expression myself. Standard deviation is basically measure of how spread out your data values are.

Analyzed step by step:

1. Take the mean of the data. (Symbol is x with bar over it)
2. For each data point, subtract mean from the data point. Then square this difference.
4. Divide this sum by number of terms minus 1. (Symbol of number of terms is n.)
5. Take square root.

For example:

Data set: 1, 3, 5, 7, 9

1. Mean = 5
2 and 3. (1 minus 5)^2 + (3 minus 5)^2 + ... = 40
4. 40 divided by (5 minus 1) = 8
5. Square root of 8 = 2.828

Standard Deviation = 2.828

Note:If your data includes possible data points for a population, then in step 4 you would instead divide by the number of terms. But if you're working with a sample of the data, which is probably the case in XPD, you divide by number of terms minus 1.

Ex. If you're analyzing the height of ALL students in your grade level, then you divide by number of data values. If you analyze the height of a randomly selected, representative sample of students in your grade level, you divide by number of data values minus 1.

Alternatively, since you can calculate Standard Deviation on your Scientific/Graphing calculator. Plug data in Stat, and use 1-var stats. Standard deviation is round-greek symbol with line out.

Good luck

Phys1cs
Member
Posts: 129
Joined: November 10th, 2013, 6:53 pm
State: MD

### Re: Experimental Design B/C

Hey Heavyhitter!

So I've always been confused by that big complicated expression myself. Standard deviation is basically measure of how spread out your data values are.

Analyzed step by step:

1. Take the mean of the data. (Symbol is x with bar over it)
2. For each data point, subtract mean from the data point. Then square this difference.
4. Divide this sum by number of terms minus 1. (Symbol of number of terms is n.)
5. Take square root.

For example:

Data set: 1, 3, 5, 7, 9

1. Mean = 5
2 and 3. (1 minus 5)^2 + (3 minus 5)^2 + ... = 40
4. 40 divided by (5 minus 1) = 8
5. Square root of 8 = 2.828

Standard Deviation = 2.828

Note:If your data includes possible data points for a population, then in step 4 you would instead divide by the number of terms. But if you're working with a sample of the data, which is probably the case in XPD, you divide by number of terms minus 1.

Ex. If you're analyzing the height of ALL students in your grade level, then you divide by number of data values. If you analyze the height of a randomly selected, representative sample of students in your grade level, you divide by number of data values minus 1.

Alternatively, since you can calculate Standard Deviation on your Scientific/Graphing calculator. Plug data in Stat, and use 1-var stats. Standard deviation is round-greek symbol with line out.

Good luck
Standard deviation is somewhat different from other statistics needed for this event. Unlike the mean, which is an average (a reference number), or the range, (a specific reference point for data values), standard deviation is how much your data should deviate from the mean. Within +/- 3 standard deviations of the mean, (if your mean is 5 and your deviation 1, that would be from points 2 through 8) around 97% of your data should be there. It makes a nice bell curve, if your data is good. Something like 70 ish % should be one standard deviation away.

So be careful when explaining the significance of this particular stat

Unome
Moderator
Posts: 4084
Joined: January 26th, 2014, 12:48 pm
State: GA
Location: somewhere in the sciolyverse

### Re: Experimental Design B/C

Oh... I always did standard deviation without the squares.
Userpage
Chattahoochee High School Class of 2018
Georgia Tech Class of 2022

Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

awesome90220
Member
Posts: 158
Joined: March 10th, 2012, 5:19 pm
Division: B
State: AL
Location: somewhere on this cruel, harsh planet

### Re: Experimental Design B/C

Apart from the usual mean, median, mode, standard deviation, and line of best fit, what are some other statistics that might come in handy at the competition(divison b)
2016 Season: BISOT/Reg/State/Nats
Wind Power:9/1/1/11
Experimental Design:5/1/1/16

HeavyHitter406
Member
Posts: 45
Joined: April 13th, 2014, 5:50 pm
Division: C
State: IL

### Re: Experimental Design B/C

Apart from the usual mean, median, mode, standard deviation, and line of best fit, what are some other statistics that might come in handy at the competition(divison b)
I think they look for range (highest data value-lowest data value).
2014 (Wright State/Lisle/Grayslake/Regionals/State/Nationals)

Water Quality: 8/1/2/1/2/3
Experimental Design: 12/1/5/5/8/37
Wheeled Vehicle: 32/6/6/2/11/5

HeavyHitter406
Member
Posts: 45
Joined: April 13th, 2014, 5:50 pm
Division: C
State: IL

### Re: Experimental Design B/C

Hey Heavyhitter!

So I've always been confused by that big complicated expression myself. Standard deviation is basically measure of how spread out your data values are.

Analyzed step by step:

1. Take the mean of the data. (Symbol is x with bar over it)
2. For each data point, subtract mean from the data point. Then square this difference.
4. Divide this sum by number of terms minus 1. (Symbol of number of terms is n.)
5. Take square root.

For example:

Data set: 1, 3, 5, 7, 9

1. Mean = 5
2 and 3. (1 minus 5)^2 + (3 minus 5)^2 + ... = 40
4. 40 divided by (5 minus 1) = 8
5. Square root of 8 = 2.828

Standard Deviation = 2.828

Note:If your data includes possible data points for a population, then in step 4 you would instead divide by the number of terms. But if you're working with a sample of the data, which is probably the case in XPD, you divide by number of terms minus 1.

Ex. If you're analyzing the height of ALL students in your grade level, then you divide by number of data values. If you analyze the height of a randomly selected, representative sample of students in your grade level, you divide by number of data values minus 1.

Alternatively, since you can calculate Standard Deviation on your Scientific/Graphing calculator. Plug data in Stat, and use 1-var stats. Standard deviation is round-greek symbol with line out.

Good luck
Thanks! I will have to look through a couple times to make sure I've got it, but seems legit! :]
2014 (Wright State/Lisle/Grayslake/Regionals/State/Nationals)

Water Quality: 8/1/2/1/2/3
Experimental Design: 12/1/5/5/8/37
Wheeled Vehicle: 32/6/6/2/11/5

Panda Weasley
Member
Posts: 133
Joined: September 27th, 2014, 6:24 am
Division: C
State: -
Location: Ravenclaw Tower

### Re: Experimental Design B/C

Does anyone know if Division B people get bonus points for doing Standard Deviation? Also, does anyone have any pointers on how to get maximum points (and or bonus points)?
DFTBA!
Events 2019: Forensics and Fossils
Proud member of Teh Ento Cult.

XJcwolfyX
Member
Posts: 340
Joined: October 22nd, 2010, 7:57 am
Division: C
State: -

### Re: Experimental Design B/C

Hi Panda! No, you do not receive extra credit or extra points for having Standard Deviation for Division B.

If you would like tips and hints about the event, please join us on the IRC Chat (Chat button on the top bar) or PM me!
Medal Counter: 73

illusionofconfusion
Member
Posts: 45
Joined: September 18th, 2011, 1:20 pm
Division: C
State: AL

### Re: Experimental Design B/C

Does anyone have a good way to distinguish between what goes in the conclusion and what goes in the analysis? Most of the time it seems to me like they're the same.
~illusionofconfusion

Panda Weasley
Member
Posts: 133
Joined: September 27th, 2014, 6:24 am
Division: C
State: -
Location: Ravenclaw Tower

### Re: Experimental Design B/C

The Analysis is a summery of what happened during the test. You are basically summarizing your results and discussing the data points. If there are any unusual data points or trends you noticed this is where you would write about them. You DO NOT discuss your hypothesis here!
The Conclusion is whether your hypothesis was supported or unsupported based on your data, and explaining why.

They do seem pretty similar, when I first started I was very confused by it. I don't really have a good method of remembering which is which though. Something that does help me though is the Analysis is analyzing the data while the Conclusion is concluding the report. Does that help at all? Maybe someone else here will have a better method.
DFTBA!
Events 2019: Forensics and Fossils
Proud member of Teh Ento Cult.

XJcwolfyX
Member
Posts: 340
Joined: October 22nd, 2010, 7:57 am
Division: C
State: -

### Re: Experimental Design B/C

Analysis:
Say all of your data. You have to mention every data point, including your averages. Then, discuss unusual data points. Make sure you're specific...such as "The time of 2.67 seconds in the 20 cm tall ramp height data was an unusual data point..." and then explain it: "...this could have been caused by...X, Y, Z." If there are no unusual data points, say that. Do not emit that from your analysis. Then, discuss the trends. "As the ramp height increased, the amount of time it took the ball to roll down it and across the floor 1 meter decreased." Then, support this with data. "This is shown because the average times for ramp heights 10 cm, 20 cm, and 30 cm were 2.90, 2.63, and 2.11, respectively. Clearly, these numbers are increasing."

Conclusion:
For your conclusion, you restate and evaluate your hypothesis. "Our hypothesis that said ________ (restate the whole thing here) was correct/incorrect (choose one). This is shown in the data because the average for the 10 cm, 20 cm, and 30 cm ramps were X, Y, Z respectively (yes, you just said this above), which shows a clear increase/decrease in time." Then, you should give a reason why this happened. "This is most likely because (scientific explanation here, such as "as you increase the ramp height, the ball begins with more potential energy and therefore has more kinetic energy when it comes to the bottom of the ramp")......

Hope this helped.
Medal Counter: 73

illusionofconfusion
Member
Posts: 45
Joined: September 18th, 2011, 1:20 pm
Division: C
State: AL

### Re: Experimental Design B/C

Okay, that really helps! I had noticed that I was writing almost the same thing for both, and I was confused, but now I'm not!
~illusionofconfusion

CulturallyScientific
Member
Posts: 176
Joined: December 29th, 2011, 7:13 pm
State: CA
Location: Berkeley, CA

### Re: Experimental Design B/C

Has anyone thought of including "analyze quantitative data with statistical tools, such as T-Test, Chi-Square test, etc" in the recommendations? I only relatively recently learned more about statistics and ExCel, so just wondering if this crossed anyone else's mind.
'16, she/her, environmental-scientist-to-be: green gen, invasives, disease, ex. design, widi.

"…everything flows in an eternal present." (James Joyce)