Variance is the average of the squared deviations from the arithmetic mean. The standard deviation is a square root from variance value. The standard deviation is a measure of the variability of values around the mean and is meant to be used with values that are normally distributed (e.g., follow a normal curve).
This integrated the seat belts and airbag into a restraint system, rather than the airbag being considered an alternative to the seat belt. In 1987, the Porsche 944 turbo became the first car to have driver and passenger airbags as standard equipment. The Porsche 944 and 944S had this as an available option. The same year also saw the first airbag in a Japanese car, the Honda Legend.
An air bag module has three main parts: the air bag, the inflator, and the propellant. The air bag is sewn from a woven nylon fabric and can come in different shapes and sizes depending on specific vehicle requirements. The driver's-side air bag material is manufactured with a heat shield coating to protect the fabric from scorching, especially near the inflator assembly, during deployment.