Bootstrapping (statistics) In univariate problems, it is usually acceptable to resample the individual observations with replacement (case resampling below). In small samples, a parametric bootstrap approach might be preferred. For other problems, a smooth bootstrap will likely be preferred.
Below is a picture of a sound wave that has. been changed into alternating current by a microphone. and displayed on a CRO. If the sound is made louder and with a higher pitch, the shape of the wave changes as shown below. The amplitude has got bigger because the sound is louder. The frequency has increased. (there are more complete waves in the same time) because the sound has a higher pitch.
Sound waves traveling through the air or other mediums sometimes affect the objects that they encounter. Recall that sound is caused by the molecules of a medium vibrating. Frequency refers to the number of vibrations that an individual particle makes in a specific period of time, usually a second. Shorter strings have higher frequency and therefore higher pitch. 2  When a musician presses her finger on a string, she shortens its length. 3  The more fingers she adds to the string, the shorter she makes it, and the higher the pitch will be. 4  Diameter is the thickness of the string.