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.
When sound changes mediums (enters a different material) at an angle other that 90 degrees, it is bent from its original direction. This change in angle of direction is called refraction. Because of the angle, part of the wave enters the new medium first and changes speed.The difference in speeds causes the wave to bend. The velocity of sound in each material is determined by the material properties (elastic modulus and density) for that material.his change in angle of direction is called refraction. Because of the angle, part of the wave enters the new medium first and changes speed. The difference in speeds causes the wave to bend. The velocity of sound in each material is determined by the material properties (elastic modulus and density) for that material.