New study says Sen. Bernie Sanders wealth tax plan may not be effective

A Wharton study finds Sanders' wealth tax would raise $2.8 trillion to $3.3 trillion over 10 years, about $1 trillion to $1.5 trillion shy of campaign estimates. Advocates of the Sanders plan say the government programs could also lead to improved worker productivity through a healthier, smarter workforce. The paper also found that former Vice President Joe Biden's plan would raise $600 billion to $900 billion less than his campaign estimates. CNBC's Robert Frank reports.