Online gambling has become increasingly popular but for a small minority of players can be problematic (∼5 percent). Many socially responsible online gambling operators have introduced responsible gambling tools to help their players stay in control of their gambling such as monetary limit-setting (in which gamblers predetermine the amount of money they want to spend per day/week/month on gambling). Despite the widespread introduction of such tools, few studies have evaluated their efficacy. This study comprised of an anonymized dataset of 49,560 players who had placed at least one wager with the online gambling operator .

The primary aim of the study was to examine whether the setting of voluntary monetary limits (independent variable) had any effect on online gambling expenditure over a 1-year period (dependent variable). The secondary aim was to examine whether there were any differences in gambling expenditure by gender, age, or gambling intensity ("gambling intensity" was simply operationalized as the total amount of money wagered during a 3-month period). Results demonstrated that there were no differences with regard to age and gender but that among the most gambling-intense players, those who had voluntarily set limits gambled significantly less money a year later compared with those who had not. Given that those individuals with the highest gambling intensity are more likely to comprise problem gamblers, limit-setting appears to be an effective responsible gambling tool because the top 10 percent of most gambling-intense individuals in this study significantly reduced their gambling expenditure over a 1-year period.