Why was The 1992 presidential election unpredictable?

The 1992 presidential election was unpredictable because the candidates included independent candidate H. Ross Perot who received 19% of the popular vote for President.

William Clinton won the 1992 presidential election defeating incumbent President George Bush and independent candidate H. Ross Perot. In the 1992 presidential election William Clinton received 370 electoral votes and George Bush received 168 electoral votes. The popular vote totals were Clinton 44,908,254 and Bush 39,102,343. Independent candidate H. Ross Perot received 19,741,065 popular votes for President, but no electoral votes.