Michal Kvasnička

Viral Video Diffusion in a Fixed Social Network: An Agent-based Model

Abstract Agent-based computational papers on viral marketing have been so far focused on the study of the word-of-mouth knowledge diffusion, and hence merged the decisions to adopt a product and to share information about it. This approach does not seem to capture well the properties of viral videos which are shared with no regard whether the sender has adopted the product. This paper presents the first model of such knowledge diffusion. The model consists of an artificial social network (a mix of small world and power network) that mimics the properties of empirical social networks and a model of node activation where every node that viewed the viral video shares it with a random subset of her neighbors just once. The results of the simulation show that there is a phase transition: in one phase, almost no agents view the viral video, in the other one, a great part of the whole population does. When the second phase occurs, the diffusion of the knowledge in time resembles that of Bass model. What phase occurs and how many agents view the content depend above all on how “catchy” the video is. Other marketing practices as selecting the seed of the first addressed agents are of secondary importance. The marketer can choose between addressing fewer more connected agents or more agents with fewer connections. If the video is “catchy”, then a small number of the first addressed agents is sufficient even when the agents are selected randomly.

Modely a metody regulace konkurenčního prostředí na trhuželezničních dopravních služeb.

Kniha podava souhrnný přehled o soucasnem stavu teoretickeho poznani a modelovani v oblasti fungovani a regulace intermodalni a intramodalni konkurence na trhu železnicnich dopravnich služeb s důrazem na evropske realie a o metodach detekce poruseni regulacnich pravidel a možnostech aplikace napravných opatřeni. Kapitoly obsahuji komentovaný souhrn teoretických konceptů dane problematiky založený na resersi publikovaných odborných textů a přiklady využiti popisovaných metod na zakladě vlastniho výzkumu autorů knihy. Prvni kapitola se zabýva soucasným stavem teoretickeho poznani v oblasti zavaděni konkurence na evropských, původně statnich, monopolnich trzich železnicni dopravy a dale praktickou implementaci železnicnich reforem v clenských zemich EU. Druha kapitola shrnuje kvantitativni techniky použitelne pro empiricke zkoumani stavu a intenzity konkurence na železnici a modelovani poptavky po železnicni dopravě; v zavěrecne casti kapitoly je provedena komparativni analýza jednotlivých modelových přistupů na zakladě dat evropských železnicnich dopravců. Ve třeti kapitole jsou představeny mikroekonomicke přistupy k modelovani struktury odvětvi železnicni dopravy, cenove regulaci a investic do infrastruktury s aplikaci statickeho a dynamickeho efektu režimů regulace. Ctvrta kapitola popisuje metody vymezovani relevantniho trhu na zakladě SSNIP testu, cenových testů, analýzy kriticke ztraty a spotřebitelských setřeni a analyzuje specifika tzv. bidding markets; v zavěru kapitoly je provedena prakticka aplikace vymezeni relevantniho trhu v osobni železnicni dopravě. Pata kapitola se zabýva geografickými přistupy k modelovani železnicniho dopravniho trhu a aplikaci geograficke metody vymezeni relevantniho trhu. Posledni, sesta kapitola dava přehled o využiti dřive popsaných metod ve skutecných postupech soutěžnich autorit ve vzorových zemich Velke Britanii a Německu a o aplikaci soutěžni politiky Evropskou komisi.

Determinants of Gratuity Size in the Czech Republic:Evidence from Four Inexpensive Restaurants in Brno

Abstract The paper presents the results of the first study exploring what factors influence tipping in restaurants in the Czech Republic. It shows that the tipping norm evolved here into a form that has some features similar to the tipping norms known in the USA, Canada, and Israel, but there are also striking differences. As in the three countries, the gratuity increases with the bill size but the gratuity as percentage of the bill is much lower here. The bill size explains here a lower part of the gratuity variability too. Also, the service quality results in customers being more generous with their tips, and though the increase in gratuity seems to be small, it rises with a group size. Strikingly, the regular patrons tip significantly less in the Czech Republic and they stiff more often. This supports the hypothesis that the relationship between the customer frequency and the gratuity size is an artifact of a missing variable, and the regular patrons tip differently because they belong to a different social group than occasional customers. Also, the customers paying by card stiff more often here and the interaction between the amount on the bill and use of payment card is statistically insignificant. The group size lowers the percentage gratuity, which supports the diffusion of the responsibility hypothesis. There are differences between genders: Male customers leave bigger tips than female customers, and female waitresses earn more than their male colleagues. The time spent at the table, consumption of alcoholic beverage, and smoking do not change the gratuity size but it may be affected by the weather conditions. The customers tip less and stiff more often when they order a lunch special. They round the total expenditures, not the gratuities, which creates the magnitude effect.

Do Auctions Improve Public Procurement? Evidence from the Czech Republic

Abstract This paper explores the effect of various contract-awarding procedures in public procurement on the price of the contract. We provide a theoretical model that compares prices in different procedures and tests whether there is a significant price difference between the procedures using data from Czech public procurement. The model predicts that auctions are more efficient than negotiations given the same number of suppliers, and open procedures are more efficient than closed procedures if high-cost firms are selected for the closed procedure. In accordance with the first prediction, we find that open auctions are more efficient than open negotiations. Concerning the second prediction, we find that closed procedures are less efficient than open procedures, which suggests that procurers tend to select relatively more costly firms to participate in closed procedures. Comparing all four awarding procedures, we find that open auctions are the most efficient procedure used in the Czech Republic. We estimate that the inefficiencies due to the use of other contract-awarding procedures are substantial.

Access Pricing Under Imperfect Competition Reconsidered

Abstract This paper claims that Onemli’s results published in “Access Pricing under Imperfect Competition”, Review of Economic Perspectives, 2012, are incorrect. Contrary to Onemli, we claim that in an industry, where a monopoly incumbent produces a key input used by itself and its competitors on a downstream market which is Cournot oligopoly, the regulator should set the second-best access charge such that the incumbent’s total profit is zero if the first-best access charge is not feasible. The competitors’ ability to produce the key input themselves does not change the outcome since no competitor chooses to use this option under this regulation. We also discuss some limitations of the Onemli’s model.