def npv_converter(sensitivity, specificity, prevalence):
    """Generates the Negative Predictive Value from designated Sensitivity, Specificity, and Prevalence.

    Returns negative predictive value

    sensitivity:
        -sensitivity of the criteria
    specificity:
        -specificity of the criteria
    prevalence:
        -prevalence of the outcome in the population
    """
    if (sensitivity > 1) or (specificity > 1) or (prevalence > 1):
        raise ValueError('sensitivity/specificity/prevalence cannot be greater than 1')
    if (sensitivity < 0) or (specificity < 0) or (prevalence < 0):
        raise ValueError('sensitivity/specificity/prevalence cannot be less than 0')
    spec_nprev = specificity * (1 - prevalence)
    nsens_prev = (1 - sensitivity) * prevalence
    npv = spec_nprev / (spec_nprev + nsens_prev)
    return npv