View definitions of terms used throughout the Pathways Clearinghouse.
An organized or structured form of learning on the job, typically in a skilled trade, but typically not subsidized.
After individuals in a study are randomly assigned to the group receiving the intervention (the intervention group) or the group not receiving the intervention (the comparison group), they might drop out of an intervention or the study team might lose contact with them. This means information about how they fare over time is no longer available for use in the in the study. This dropping out is called attrition. The proportion of people who drop out of a study is called the attrition rate. There are two different types of attrition that matter when deciding whether a study’s findings can be considered reliable. The first is overall attrition, which captures the total number of individuals missing from the original sample. The second is differential attrition which captures the difference between the percentage of individuals missing from the intervention group and the percentage missing from the comparison group. When either the overall attrition or the differential attrition is too high, the study results might not accurately capture the effects of the intervention. We use scientific standards to determine when either of these types of attrition is too high for a study’s findings to be considered reliable.