First, none of the studies on buffer stocks control for any other factors that could have contributed to price volatility. In particular, the role of trade policies, actions of private traders, private stocks, the macroeconomic environment, and production levels in (de)stabilising prices are ignored in most of the studies and certainly are not accounted for in any empirical analysis. At best, a study will mention the confounding factors. This is not a criticism as it is indeed an extremely complex, if not impossible, task to disentangle the impact of trade policies, macroeconomic factors and domestic policies on price volatility. This is not surprising as buffer stocks are by nature more adapt at preventing price drops (guaranteeing a floor price) than curtailing price spikes (maintaining a ceiling price). This relates back to the point mentioned above regarding the natural limit of stocks: once stocks are depleted, the buffer stock can no longer prevent price rises.