Insufficient effort responding (IER) refers to a lack of effort when answering survey or questionnaire items. Such items typically offer more than two ordered response categories, with Likert-type scales as the most prominent example. The underlying assumption is that the successive categories reflect increasing levels of the latent variable…

The attitude of teachers towards inclusive education is a key issue for the success of inclusive education. Many studies have been designed to assess teachers' attitudes, but none have looked at the bias caused by teachers' non-response to questionnaires on their attitudes. Non-response biases are difficult to identify because it is impossible to…

Using secondary data has many advantages, but there are also many limitations, including the lack of relevant information. This article draws on a previous study that used secondary data to investigate substance use in young, elite athletes. Three types of missing data appeared: missing data, lack of information about the data collection process,…