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# Defining measured variables

What are you trying to measure or infer in your research project?  Addressing this question leads you to identifying the variables in your work.  Identifying the relevant metrics, and their associated units, is essential in carrying out a meaningful research project.  Measured variables are values which are directly measured by an observer, such as using a ruler for length or a thermometer for temperature.

If your research project involves a study of the relationship between the median income of a neighborhood and the availability of grocery stores then the measured variables involved could be:

1. Median income per zip code (\$US)

2. GPS coordinates of grocery stores (degrees latitude, degrees longitude)

3. Area of zip code (square kilometers)

At this point you'll want to identify what you're measuring in the course of your work, as well as what units you'll be using in which to measure them.

• We're giving the LED lights numerical names measure by nm and their wavelength. (Bioscan)

Yellow- 587

UV- 390

Green- 535

Blue- 469

Red- 661

White- 500

Orange- 610

For further reference, see http://www.livephysics.com/physical-constants/optics-pc/wavelength-colors/.

• The wavelength listed for white is an average of the yellow and blue component wavelengths used in most white LEDs: http://www.oksolar.com/led/led_color_chart.htm

• UNITS!

1. Longitude and latitude: degrees
2. altitude: meters or ft
3. Accelerometer: m/s^2
5. Light: lux
6. Magnetic field: micro teslas
7. Orientations (I am not sure the difference between gyroscope i think it measures poition in x y z rotation while gps measures angular velocity): degrees
8. Proximity (my phone can only report whether or not something is within 2 inches of the sensor) inches
9. Sound level: dB
10. Battery level: percent
11. internel (battery) temp: fahrenheit or celsius
12. Atmospheric pressure: millibar
13. Time: date and hh:mm:ss
• For this project we'll be using the following using only metric.

• Currently android phones can measure:

1. GPS + altitude
2. Accelerometer
3. Gyroscope
4. Light
5. Magnetic field
6. Orientations (I am not sure the difference between gyroscope howeAtmospheric pressure
7. ver the phone reports degrees rather than rads)
8. Proximity (my phone can only report whether or not something is within 2 inches of the sensor)
9. Sound level
10. Battery level

Ideas for use of sensors:

1. MASS WEATHER STATIONS!!! (only with new phones)  FLY THEM IN BALOONS OVER THE OCEAN!!! (this could help: )
2. Solar flares with magnetic field data
3. Earthquake detection with accelerometer
4. TBC!
• Max,

Could you start putting together an online spreadsheet grouping sensors to possible projects, or projects which have already been done?

• We'll get on that
• Shared, and here is the link: