Final answer:
Blue collar workers are likely the class of employees for which letters of reference are used less often in Canadian companies, due to the practical skills required for these roles and changes in hiring practices due to outsourcing and streamlining.
Step-by-step explanation:
The study you're referring to likely examines the hiring practices within Canadian companies. When considering which classes of employees letters of reference are used less often in the selection process, the options given are managerial, professional, white collar, and blue collar workers. Given the context provided and the trends in hiring practices, blue collar workers are likely the category that is the exception, meaning that letters of reference are used over 75% of the time for all classes except for blue collar employees.
This is because blue collar jobs often focus more on manual labor and practical skills, which are less likely to be verifiable through letters of reference compared to the expertise typically required in managerial and professional roles. Moreover, with the rise of outsourcing and streamlining within companies, there has been a shift in how various job roles, especially blue collar and low-level white collar positions, are valued and recruited. Thus, employing traditional methods such as letters of reference may not be as prevalent in these areas.