each doubling of technological advancement requires four-times

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Maybo

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In his analysis of the paper, MacAskill estimates that each doubling of technological advancement requires four-times as much research effort as the previous doubling.
(Do we need a better understanding of 'progress'? by Garrison Lovely)

Why do we need a hyphen in the above sentence? Is it because "four-times" sticks to "research effort"?
 
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