Rezensionen

Ohne Zusammenfassung     

Rezensionen

Ohne Zusammenfassung     

Rezensionen

Ohne Zusammenfassung     

Characterization of the exponential distribution function by Properties of the differenceX k+s∶n−X k∶n of order statistics

We considern independent and identically distributed random variables with common continuous distribution functionF concentrated on (0, ∞). LetX _1∶n≤X_2∶n...≤X_n∶n be the corresponding order statistics. Put $$d_s \left( x \right) = P\left( {X_{k + s:n} - X_{k:n} \geqslant x} \right) - P\left( {X_{s:n - k} \geqslant x} \right), x \geqslant 0,$$ and $$\delta _s \left( {x, \rho } \right) = P\left( {X_{k + s:n} - X_{k:n} \geqslant x} \right) - e^{ - \rho \left( {n - k} \right)x} ,\rho > 0,x \geqslant 0.$$ Fors=1 it is well known that each of the conditions d₁(x)=O ?x≥0 and δ₁ (x, p) = O ?x≥0 implies thatF is exponential; but the analytic tools in the proofs of these two statements are radically different. In contrast to this in the present paper we present a rather elementary method which permits us to derive the above conclusions for somes, 1≤n —k, using only asymptotic assumptions (either forx→0 orx→∞) ond _s(x) and δ₁ (x, p), respectively.     

Success breeds success. The dynamics of the innovation process

This paper presents a dynamic random effects probit model for the realization of private firms' product and process innovations. We estimate the model with panel data collected by the Ifo Institute in Munich. The data covers the period between 1979 and 1986 and includes 301 firms of the West German manufacturing sector. It turns out that firms' probabilities of innovation depend on market structure, demand and cost expectations, unobserved heterogeneity, and realized innovations in the previous year. The positive significant influence of past innovations indicates that there is strong state dependence in the innovation process. This result supports the success breeds success hypothesis suggesting a positive impact of innovative success to further innovations in the following years.We would like to thank the Ifo-Institute for providing us with the data of the Ifo-Konjunkturtest. Special thanks to Georg Licht and Horst Rottmann for preparing the data. Helpful comments were received from participants of seminars in Mannheim, Hannover, and Nürnberg, especially from Dietmar Harhoff. We are particularly indebted to an anonymous referee for valuable suggestions. Financial support of the DFG is gratefully acknowledged.