'Lockouts are a phenomenon greatly underestimated in research into labour relations. Despite the ILO recommendations many national statistical bureaus do not make a distinction between strikes and lockouts. This practice leads to false conclusions about workers' behaviour. After all, strikes and lockouts are two sides of the medal of labour relations but really two different sides. Strikes are a weapon of workers, whereas lockouts can be a means by which employers force their workers into a certain direction. The data on labour relations should therefore discriminate between strikes and lockouts. Because the official data often neglect this, it may be necessary to do own research into the subject. This article shows the argument for discrimination taking the Netherlands as an example with some references to other countries.' (author's abstract)