Interesting article here today from Chris Leithner -

https://www.livewiremarkets.com/wires/the-myth-of-small-cap-outperformance?utm_campaign=87365&utm_content=wrap_up_instant&utm_term=the-myth-of-small-cap-outperformance&utm_medium=email&utm_source=campaign+monitor

He's not a "concise" writer but he does always use a lot of data and evidence to back up his assertions.

Personally I wonder whether lots of our speculative miners might be why our small cap index seems to underperform over the long term? I am still finding enough financially healthy, profitable and growing small companies at fair valuations, so will keep reviewing bottom up on their individual merits.

Morningstar also published this chart today that seems to support much of what Chris Leithner suggests over the longer term, for small caps as a basket.