Imagine that you're looking at your company-issued smartphone and you notice an e-mail fromLinkedin："These companies are looking for candidates like you!"You aren't necessarily searchingfor a job，but you're always open to opportunities，so out of curiosity，you click on the link．A fewminutes later your boss appears at your desk．"We've noticed that you're spending more time onLinkedin lately，so I want to talk with you about your career and whether you're happy here，"shesays．Uh-oh．

It's an awkward scene．Attrition（损耗） has always been expensive for companies，but in manyindustries the cost of losing good workers is rising，owing to tight labor markets．Thus companies areintensifying（增强） their efforts to predict which workers are at high risk of leaving so that managerscan try to stop them．Tactics（策略） range from electronic monitor to sophisticated（复杂的） analysesof employees'social media lives．

Some of this work may be a reason to let employees to quit．In general，people leave theirjobs because they don't like their boss，don't see opportunities for promotion or growth，or are offereda higher pay； these reasons have held steady for years．

New research conducted by CEB，a Washington-based technology company，looks not just atwhy workers quit but also at when．"We've learned that what really affects people is their sense ofhow they're doing compared with other people in their peer group，or with where they thought theywould be at a certain point in life，"says Brian Kropp，who heads CEB's HR practice．"We've learnedto focus on moments that allow people to make these comparisons．"

Technology also provides clues about which star employees might be eyeing the exit．Companiescan tell whether employees usmg work computers or phones are spending time on （or even justopening e-mails from） career websites，and research shows that more firms are paying attention tothese things．Large companies have also begun tracking bad