  In economy, markets are denoted as efficient when it is impossible to
systematically generate profits which outperform the average. In the past
years, the concept has been tested in other domains such as the growing sports
betting market. Surprisingly, despite its large size and its level of maturity,
sports betting shows traits of inefficiency. The anomalies indicate the
existence of strategies which shift betting from a game of chance towards a
game of skill. This article shows an example for an inefficiency detected in
the German soccer betting TOTO 13er Wette, which is operated by state-run
lottery agencies. Gamblers have to guess the outcome (win, draw, loss) of 13
soccer matches listed on a lottery tip. Applying stochastic methods, a recipe
is presented to determine hit rates for single match outcomes. More important,
the recipe provides the number of lottery tips required to achieve a specific
number of strikes (number of correct match forecasts per lottery tip) for any
given level of safety. An approximation is derived to cope with large numbers
in hypergeometric distributions, valid under certain constraints. Overall, the
strategy does lead to returns exceeding the aggregated lottery fees, resulting
in moderate, but consistent profits. It is briefly discussed if lessions
learned from soccer betting can be transferred back to financial markets,
because gamblers and retail investors face similar challenges and
opportunities.
