The greatest edge an ASX shares investor can have is a good temperament, says Nathan Robertson, CEO of Alvia Asset Partners.

Not information, not analytical skills, not even experience. Just a nice, even temperament.

Writing in the Weekend Australian, Robertson says temperament affects how an investor will handle market volatility.

Robertson's company is an independent family office investment manager that espouses the virtues of high-conviction investing.

He says one aspect of temperament is thoughtful stock selection.

Having conviction in the ASX shares you choose to invest in makes you more resilient when markets are turbulent, he says.

That requires a thorough research and stock selection process you trust, as Robertson explains:

I've seen people cut great businesses from their portfolios because they couldn't stomach the headlines.

I've seen others add to positions during chaos, trusting in the work they'd done.

Resilience is about having a process that you trust.

Another component of temperament is patience.

Robertson comments:

Patience sounds like a cliché until you see how rare it really is.

In a world wired for immediacy, it takes real discipline to sit still.

I've seen solid investment strategies unravel, not because they were wrong, but because someone couldn't resist the lure of a quick win, or let fear drive a rushed sell.

Robertson shares two stories in which losing patience with one ASX stock led to missed gains, while staying the course with another resulted in a very big win.

'Patience isn't passive': expert

Robertson says, "Patience isn't passive". In other words, it takes strength to look past the daily headlines and focus on the long term.

He elaborates:

It's about having a clear idea of what you're looking for and being willing to wait for it.

That's harder than it sounds.

In 2022, Robertson and his team bought A2 Milk Company Ltd (ASX: A2M) for about $5 per share.

He explained their thesis:

Operational metrics had deteriorated, but with a strong balance sheet we thought they were poised for a turnaround in Asia.

In 2024, the team lost patience with the ASX consumer staples share.

Robertson laments:

After two years of little progress we figured the company had the turning circle of a submarine and exited at roughly our entry price, having made no money.

Since then, the stock has rallied about 60%.

The thesis wasn't necessarily wrong. We just didn't stay the course.

ASX shares: The big black swan

There's nothing like a black swan event to rattle investors, and COVID was arguably the mother of black swans.

In March 2020, Robertson and his team decided to stay invested and "leaned into businesses priced for Armageddon".

ASX consumer discretionary stock Nick Scali Limited (ASX: NCK) was one of them.

Robertson tells the story:

The stock fell about 60% in the pandemic sell-off.

But its business model, with minimal working capital and excellent visibility on earnings, were traits we valued when others didn't.

Were people never going to buy furniture again because of a pandemic? We thought not.

We still own it today, following a 500% rally from its Covid lows.

Holding on has taken real conviction.