In some cases it is an offense by itself to plan or attempt to commit a crime; this in called an inchoate offense. Examples of inchoate offenses include conspiracy to commit murder and attempted burglary. There can be various causes of failing in the attempt, for example arrest prior to committing the crime.
... under the age of 18 living with them, 61.4% are married couples living together, 10.5% have a female householder with no husband present, and 26.3% are non-families. 16.7% ...