Even if we accept the numbers for the effects of government-funded R&D, over the decades the government-funded research establishment has become increasingly inefficient and bloated with administration. So much funding goes to work that has little, no, or negative return. Past returns are no guarantee of future returns! Rather than increasing government spending, first deregulate to improve the efficiency and effectiveness of current spending.
Two quick thoughts about government R&D spending - First, I suspect that it has become much less impactful since the 1960s because (a) the indirect cost rate for government grants (i.e. how much gets diverted to university administration) has risen a lot, making $1 in R&D spending much less than $1 dollar in actual R&D) and (b) government R&D spending comes with much more red tape than it used to (funded, in part, by (a)). So one way to improve government R&D spending would be to cut both (a) and (b), increasing the proportion of R&D spending that actually went into. R&D.
Second, the Bayh-Dole Act was supposed to unleash the economic potential of government funded research by encouraging universities to commercialize research. It's been a bit of a damp squib. A colleague and I explored why universities are so bad at that here: https://jipel.law.nyu.edu/unpacking-coasian-red-boxes-universities-and-commercialization/ TLDR summary is that funding R&D through universities is great for universities but there are some real problems with getting university-funded research into the real world where it can enhance productivity. (Of course there are examples where university research does well - but overall, there are problems).
Even if we accept the numbers for the effects of government-funded R&D, over the decades the government-funded research establishment has become increasingly inefficient and bloated with administration. So much funding goes to work that has little, no, or negative return. Past returns are no guarantee of future returns! Rather than increasing government spending, first deregulate to improve the efficiency and effectiveness of current spending.
Two quick thoughts about government R&D spending - First, I suspect that it has become much less impactful since the 1960s because (a) the indirect cost rate for government grants (i.e. how much gets diverted to university administration) has risen a lot, making $1 in R&D spending much less than $1 dollar in actual R&D) and (b) government R&D spending comes with much more red tape than it used to (funded, in part, by (a)). So one way to improve government R&D spending would be to cut both (a) and (b), increasing the proportion of R&D spending that actually went into. R&D.
Second, the Bayh-Dole Act was supposed to unleash the economic potential of government funded research by encouraging universities to commercialize research. It's been a bit of a damp squib. A colleague and I explored why universities are so bad at that here: https://jipel.law.nyu.edu/unpacking-coasian-red-boxes-universities-and-commercialization/ TLDR summary is that funding R&D through universities is great for universities but there are some real problems with getting university-funded research into the real world where it can enhance productivity. (Of course there are examples where university research does well - but overall, there are problems).