Both statements I and II are accurate in the context of risk management. Statement I correctly points out that risk measurement can be challenging for certain asset classes due to their illiquidity. This is particularly true for real estate, venture capital, and some categories of hedge funds. Additionally, some series, such as emerging markets and initial public offerings, have very short histories, making risk measurement difficult. Statement II correctly suggests that in some cases, the missing series can be replaced by a proxy using a mapping approach. This is a common practice in risk management when dealing with illiquid assets or series with short histories.