The negative consequences of deteriorated sleep have been widely acknowledged. Therefore, research on the determinants of poor sleep is crucial. A factor potentially contributing to poor sleep is the use of a smartphone. This study aims to measure the association between overall daily smartphone use and both sleep quality and sleep duration. To this end, we exploit data on 1,889 first-year university students. Compared with previous research we control for a large set of observed confounding factors. Higher overall smartphone use is associated with lower odds of experiencing a good sleep. In addition, we explore heterogeneous differences by socioeconomic factors not yet investigated. We find that the negative association between smartphone use and sleep quality is mainly driven by female participants.

We present the first systematic review of the scientific literature on smartphone use and academic success. We synthesise the theoretical mechanisms, empirical approaches, and empirical findings described in the multidisciplinary literature to date. Our analysis of the literature reveals a predominance of empirical results supporting a negative association between students’ frequency of smartphone use and their academic success. However, the strength of this association is heterogeneous by (a) the method of data gathering, (b) the measures of academic performance used in the analysis, and (c) the measures of smartphone use adopted. The main limitation identified in the literature is that the reported associations cannot be given a causal interpretation. Based on the reviewed findings and limitations, directions for further research are discussed.

After a decade of correlational research, this study attempts to measure the causal impact of (general) smartphone use on educational performance. To this end, we merge survey data on general smartphone use, exogenous predictors of this use, and other drivers of academic success with the exam scores of first‐year students at two Belgian universities. The resulting data are analysed with instrumental variable estimation techniques. A one‐standard‐deviation increase in daily smartphone use yields a decrease in average exam scores of about one point (out of 20). When relying on ordinary least squares estimations, the magnitude of this effect is substantially underestimated. The negative association between smartphone use and exam results is more outspoken for students (i) with highly educated fathers, (ii) with divorced parents and (iii) who are in good health. Policy‐makers should at least invest in information and awareness campaigns of teachers and parents to highlight this trade‐off between smartphone use and academic performance.

We test the soccer myth suggesting that a particularly good moment to score a goal is just before half time. To this end, rich data on 1,179 games played in the UEFA Champions League and UEFA Europa League are analysed. In contrast to the myth, we find that, conditional on the goal difference and other game characteristics at half time, the final goal difference at the advantage of the home team is 0.520 goals lower in case of a goal just before half time by this team. We show that this finding relates to this team’s lower probability of scoring a goal during the second half.

Previous research on the advantage experienced by soccer teams playing the second leg of a knock-out confrontation at home yielded ambiguous evidence. Some studies confirmed the well-established soccer myth that this advantage is substantial while others did not find any significant evidence. We contribute to this literature by analysing all ‘non-seeded’ two-leg confrontations in the UEFA Champions League and the UEFA Europa League between 2010 and 2017. We find that playing the second leg of a knock-out confrontation at home is not associated with a substantially higher chance of proceeding to the next stage of the tournament.

We investigate how the goal-scoring probability in international club soccer evolves after player substitutions. To this end, we analyse rich data concerning 2,025 recent soccer games played in the two most prestigious club soccer competitions, i.e. the UEFA Champions League and the UEFA Europa League. As first in the literature, we control for within-game dynamics by applying a minute-by-minute bivariate probit approach. We find that teams experience increased goal-scoring probabilities after their first and second substitution and a decreased probability of scoring afther the three substitutions made by their opponent. This association is less distinct during the first 3 mins after the substitution, which is consistent with difficulties to adapt to (i) the game intensity by the substitute player or (ii) tactical changes by the entire team. Furthermore, we find that the change in goal-scoring probability is substantially bigger if the team is losing at the moment of the substitution.

To study the causal impact of smartphone use on academic performance, we collected—for the first time worldwide—longitudinal data on students’ smartphone use and educational performance. For three consecutive years we surveyed all students attending classes in eleven different study programmes at two Belgian universities on general smartphone use and other drivers of academic achievement. These survey data were merged with the exam scores of these students. We analysed the resulting data by means of panel data random effects estimation controlling for unobserved individual characteristics. A one standard deviation increase in overall smartphone use results in a decrease of 0.349 points (out of 20) and a decrease of 2.616 percentage points in the fraction of exams passed.

Previous studies have demonstrated a strong negative association between smartphone use and sleep quality. However, the majority of these studies quantified smartphone use with subjective self-reported metrics. In contrast, the current study contributes to the literature by objectively logging university students' smartphone use and investigating the association thereof with sleep quality. The extensive nuanced smartphone usage information obtained from this logging also enables us to explore the validity of several mechanisms theorised to underlie the previously reported negative association between smartphone use and sleep quality. In contrast to earlier research, we do not find a significant association between sleep quality and the duration or frequency of students' daily smartphone use. However, students with the internalised habit of launching a greater number of applications per session ('gateway habits') experience worse sleep quality. This finding is consistent with literature showing that smartphone-related stress is more strongly associated with checking habits stemming from 'fear-of-missing-out' than with overall screen time.