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Experiments and Variables Help (page 2)

By — McGraw-Hill Professional
Updated on Aug 26, 2011

Continuous Variable

A continuous variable can attain infinitely many values over a certain span or range. Instead of existing as specific values in which there is an increment between any two, a continuous variable can change value to an arbitrarily tiny extent.

Continuous variables are something like the set of radio frequencies to which an analog FM broadcast receiver can be tuned. The radio frequency is adjustable continuously, say from 88MHz to 108MHz for an FM headset receiver with analog tuning (Fig. 2-2). If you move the tuning dial a little, you can make the received radio frequency change by something less than 0.2 MHz, the separation between adjacent assigned transmitter channels. There is no limit to how small the increment can get. If you have a light enough touch, you can adjust the received radio frequency by 0.02 MHz, or 0.002 MHz, or even 0.000002 MHz.

Other examples of continuous variables are:

  • Temperature in degrees Celsius.
  • Barometric pressure in millibars.
  • Brightness of a light source in candela.
  • Intensity of the sound from a loudspeaker in decibels with respect to the threshold of hearing.

Experiments and Variables

Such quantities can never be determined exactly. There is always some instrument or observation error, even if that error is so small that it does not have a practical effect on the outcome of an experiment.

Practice problems for these concepts can be found at:  Learning the Statistics Jargon Practice Test

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