1. A device for implementing a top-down flow down of at least one system requirement to allocate variability to a plurality of system components, comprising: a processor circuit having a processor and a memory, said processor circuit configured to receive data corresponding to a non-linear model of the at least one system; receive data corresponding to each of the plurality of system components; receive a user selectable real number (m-value); receive the at least one system requirement; use the non-linear model data, the data corresponding to each of the plurality of system components, and the m-value to allocate variance to each of the plurality of system components such that overall system response satisfies the at least one system requirement, wherein the variance of the non-linear model is expressed by at least one of σ R 2 = ∑ i ⁢ { FS i 2 ⁢ ζ i 2 } , ⁢ ζ i = σ R ∑ j ⁢ FS j 2 ⁢ p p - 2 ⁢ FS i 2 p - 2 , ⁢ ζ i = σ R ∑ j ⁢ ( μ j ⁢ FS j ) 2 ⁢ p p - 2 ⁢ μ i p p - 2 ⁢ FS i 2 p - 2 , or σ R 2 = ∑ i ⁢ { S i 2 ⁢ σ i 2 + S i ⁢ T i ⁢ σ i 3 ⁢ SK i + [ T i ⁢ σ i 2 2 ] 2 ⁢ ( K i - 1 ) } , where σ R is the targeted variance of the response variable R, FS i is the generalized sensitivity coefficient, ζ i is the generalized variance coefficient, μ i is the mean value of, p is a real number based on the m-value S i and T i are first and second derivatives of the response, SK i is the Skewness and T i is the Kurtosis; and output the variance for each of the plurality of system components.