Some intraday data series do not contain a buy/sell identifier for trades. As most estimators of transaction costs require this information, an algorithm is necessary to classify trades as buy or sell. When bid/ask quotes (or best buy/sell limit order prices) are available, a natural method is to compare the trade price with the quotes prevailing at the time of the trade. Trades at or above the ask (or best sell limit price) will be classified as buys, trades at or below the bid (or best buy limit price) will be classified as sells. This algorithm will leave trades within the quotes unclassified. Trades within the quotes may be either ‘crosses’ (trades negotiated outside the central market place) or trades where a floor broker or the order book improved on the price of the specialist’s quote, as often happens on hybrid markets like the NYSE. Lee and Ready (1991) show that this algorithm is very reliable and classifies most trades in the same way as the classification based on a comparison with bid and ask quotes.

You can reduce the risk in starting your own small business by sticking closely to what you already know. By “what you know,” I mean (1) the product or service you are selling and (2) the primary method by which you are going to sell it.

Serially successful entrepreneurs follow this formula. They spend thousands of hours figuring out how a particular business works—and once they understand it, they seldom jump into something entirely different.

My own rule for starting a new business is this: One baby step at a time. By that, I mean that I’m willing to try something new—but just a little new. If, for example, I’ve learned how to sell cat food with banner ads on the Internet, I might consider setting up a business that sells cat food with small ads in magazines. (That’s one baby step. If I can’t figure out magazine advertising, I can get out quickly and safely.) But I wouldn’t let myself get into a business that sold cat health-care products through direct mail—even if I could convince myself that I’m an expert in selling cat products. Selling cat health-care products through direct mail is simply too many steps away from my core competence.

If you develop expertise in a particular business and don’t stray too far from it, you’ll always feel confident that you can create a new business without taking a lot of risk.

Unmanageability is a big issue with municipal bonds (munis). (Munis are bonds issued by states and local governments.) State and local government bonds are less secure than federal government bonds. The federal government can print money to pay bond interest and principal. With munis, defaults are possible, because state and local governments do not have the power to print money. Although defaults are rare, they occur. Many munis are secured by specific projects. If the project is bad, the muni could default.

Other munis are secured by a general fund. However, mismanagement of the general fund can endanger your muni. For example, the Orange County (California) general fund in 1993 and 1994 was run like a hedge fund. The fund manager invested in derivatives and leveraged up the fund just when interest rates rose dramatically, bankrupting the county. This type of mismanagement can lead to feelings of outrage among bondholders.

Munis are sometimes insured, but the insurer needs to be solid for the insurance to be any help. State and local governments sometimes establish a fund, known as a sinking fund, to be used to pay off specific bonds when they come due. These bonds are known as prerefunded bonds. Prerefunded bonds are more secure as long as the sinking fund is never attached.

Important as it is, the general ledger doesn’t exist in a vacuum, but interacts rather cleverly with other parts of a company’s accounting system. This occurs through a process called posting.

Posting is simply entering into the G/L a summary of posted directly to the general ledger include returns of merchandise, allowances from a supplier for credit, asset acquisitions, asset sales, investor capital contributions, loan drawdowns, and loans. These are called journal entries.

Transactions transactions recorded in the subledgers or journals, with a reference number. We’ll get further into the entire process later.

Some transactions are posted only to the general ledger and not to the subledgers. These transactions tend to be unusual. But proceed with caution. Items that should be entered in subledgers but are simply posted to the general ledger for the sake of convenience can throw the bookkeeping out of whack and unbalance your balance. That’s an error no accounting system can afford.