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.
Two main characteristics of the wave determine how we perceive the sound: Sound wave frequency - A higher wave frequency simply means that the air pressure fluctuates faster. The faster an engine runs, the higher the pitch we hear. Slower fluctuations sound like a lower pitch. Air pressure level - The wave's amplitude determines how loud the sound is. Sound waves with greater amplitudes move our eardrums more, and we register this sensation as a higher volume.