So here is the problem with it: The study asked for wages and salaries, loans and business revenues. No surprise salaries all over the country are in riel, except Phnom Penh and Siem Reap. In general "Dollarisation remains high, at about 80 percent."
The remaining 20 percent is used by locals for every day expenses. Most veggies fruit and grocery items are less than 5 dollar and can easily be paid in riel. everything that is more durable and expensive will be paid in dollar.
I cannot see any thing new in this fact and why it needed 200 households and 800 businesses to get a conclusion you can have by simply going to the market. Oh, maybe it is just to have a new piece of propaganda and a justification for the Japanese tax spending for JICA.