There's a simple reason for the general upward trend of prices in Beijing and, surprisingly, it has nothing to do with all that economic jargon floating around about productivity gains, wage costs and so on.

Prices are rising, simply because "all prices are going up". Or, "dou zhang jia" as it's known on Beijing's streets.

I first encountered this phrase when that cold snap hit Beijing in mid-October. Time to get the heating turned on, I thought, and called my compound's management office to make an appointment for the maintenance workers to tweak the system that changes it from air-conditioning mode to heating.

"The worker will come at 2 pm on Sunday. Make sure someone is at home and pay him 300 yuan ($45)," said the young man at the other end of the line.

"Three hundred," I sputtered. "Why? We have always paid 150 yuan. I refuse to pay double."

Perhaps a bit taken aback by the aggression in my voice, the young voice at the other end lost a bit of its practiced confidence in English and resorted to half-Mandarin: "Madam, dou zhang jia. Everybody is paying the same."

But why? I persisted. The worker is merely doing what he has done for the past three years. The system hasn't changed, so why should I have to pay double for the same five-minute job?

"Oh, now the worker will be responsible if something breaks," said my young friend, betraying clear signs of nervousness.

"What? You mean earlier he could break anything with impunity," I said.

Realizing the folly of his statement, he resorted to dou zhang jia, yet again.

"Have your earnings gone up?" I asked.

"No," came the answer with a laugh.

"Neither have mine. So what do you mean by dou zhang jia?" I hollered.

Regaining his composure, he said with a tough note of finality, "If you don't pay,no worker." And then, softening a bit, "Sorry, dou zhang jia."

Just then a cold draft of wind blew in through an open window and I quickly relented.

The next day, ayi walks in with the week's purchase of vegetables.

"Very expensive," she says in Chinese, "Dou zhang jia."

I looked at the bill. It was 50 yuan more than the previous week for the same amount of veggies. What had transpired between one week and the next to account for this rise, I wondered.

Recently, a cousin from Singapore visited and off we went to the Silk Market to do some shopping for silk. I had been there just a week earlier with another visiting relative and knew exactly where to go for my material.

Walking up confidently to the vendor, I said: "Give me six meters of this; 30 yuan a meter, right."

"Wrong," she said. "It's 40 per meter now."

"Oh, come on. You probably don't remember me. I was here just last week and bought this same stuff for 30," I said. While I have tried the same line (falsely) on countless other occasions to bargain down prices, this time I was being honest.

"I know," said the vendor with confidence.

"It was going for 30 last week but now it's 40," she said. "Dou zhang jia."

Our next stop was the tailor near where I live. A Shanghai native, he is popular in the neighborhood because his sartorial skills come at a reasonable price.

"I need to get two pairs of trousers made. So, that's 80 yuan, right?"

"Wrong. That's 120 yuan."

Why? I already knew the answer, of course.

Dou zhang jia.