hand, demand rationing increased in the other two countries as their auctions changed from competitive to Dutch pricing, with supply ratios declining from 0.90 0.87 in Nigeria, and from 0.68 to 0.45 in Zambia.

For the case of Zambia, the same story can be told for the winning to total bids ratio, which declined dramatically frm an average of 0.65 to 0.42 between tde two auction regimes. This is a direct result of the increasing frequency of interventions and bids disqualifications that took place in the Zambian auction. Interventions/disqualifications have also taken place in Nigeria; unlike Zambia, the bid total excludes these disqualifications, so that the successful ratio is high at its average of 0.86 in the competitive auction, and 0.89 in the Dutch. On the other hand, the same ratio remained high at 0.92 on average for Uganda, and was lower * 0.78'5 over the retail auction in Ghana.

The blacklauction premium rose from 1.33 to 1.59 bween the two auction pricing regimes in Zambia, while it almost remained constant ([.36 to 1.33) between the two similar regimes in the Nigerian auction. On the contrary, the buremux/auction premium declined dramatically in the Ghanaian aucion from an average of 1.31 for the retail regime to only 1.06 for the wholesale. For Uganda the premium rates averaged 1.19 o 1.24 overall.

To conclude, it is important to emphasize that the increasing (or constant) and high premia that prevailed in the Nigerian and Zambian auctions, are the uldmate outcome of the above auction design!policy mistkes in these two counries. The frequent and some imes arbirary interventionsldisqualifications have fostered an atmosphere of policy incredibility, lack of transparency and collusive behavior. In addition, the absence of a reserve price policy in the two, countries fiurder compromised stability of auction prices. For a reserve price to be sustainable, however, it has to be consisten with a stable relevant macroeconomic signal, such as the parallel or bureaux rate. Given the rather unsable macoonomic environmet dtat prevailed in these two countries during the auction experment, both the bureaux and the parallel market could not constte efficient secondary markets. These are exacdy the problems that the Ghanaian and Ugandan auctions seemed to, have avoided, hence their success at achieving exchange rate unification-the key objective of foreign exchange auction in SSA.

# 3.2 Normality **iss**

Given the results on the non-stionarity of most of the auction data (see sub-section 3.3 below), the analysis of ihis sub-section will be based on the rates of changes of the variables in question (A;xt = logX4-logX. I) The departure from normality is another characteristic freqently observed in economic data that has important implications for the analysis of variability and uncertainty. In a recent paper, Pritchett (1991) found that the time series data developing countries real exchange rates tend to be characterized by excess krtosis (relatively large probabilities of exeme observations) and skewne (tendency of extreme observations in one tail). Pritchett's results suggest that when there are significant higher order moments (skewness and/or kurtosis), the standard t Data on the number of bids as not available for the Gha whoksale auction.