Quotes About Data

Containment is the simple idea that a class contains a primitive data element or object. A lot more is written about inheritance than about containment, but that's because inheritance is more tricky and error-prone, not because it's better. Containment is the work-horse technique in object-oriented programming.

Be critical of classes that contain more than about seven data members. The

If a class contains more than about seven data members, consider whether the class should be decomposed into multiple smaller classes (Riel 1996). You might err more toward the high end of 7±2 if the data members are primitive data types like integers and strings, more toward the lower end of 7±2 if the data members are complex objects.

Global data is generally subject to two problems: routines operate on global data without knowing that other routines are operating on it, and routines are aware that other routines are operating on the global data but they don't know exactly what they're doing to it.

In most instances, global data is really class data for a class that hasn't been designed or implemented very well. In a few instances, data really does need to be global, but accesses to it can be wrapped with access routines to minimize potential problems. In a tiny number of remaining instances, you really do need to use global data.

Knowing what to measure and how to measure it makes a complicated world much less so.

It is well and good to opine or theorize about a subject, as humankind is wont to do, but when moral posturing is replaced by an honest assessment of the data, the result is often a new, surprising insight.

When moral posturing is replaced by an honest assessment of the data, the result is often a new, surprising insight.

The data don't lie: a Chicago street prostitute is more likely to have sex with a cop than to be arrested by one.

Married people, for instance, are demonstrably happier than single people; does this mean that marriage causes happiness? Not necessarily. The data suggest that happy people are more likely to get married in the first place.

Porque no hay nada como la pura fuerza de los números para retirar capas de confusión y contradicción.

that number is 58 percent

Correlation does not equal causality. When two things travel together, it is tempting to assume that one causes the other. Married people, for instance, are demonstrably happier than single people; does this mean that marriage causes happiness? Not necessarily. The data suggest that happy people are more likely to get married in the first place. As one researcher memorably put it, "If you're grumpy, who the hell wants to marry you?

The economic approach is both broader and simpler than that. It relies on data, rather than hunch or ideology, to understand how the world works, to learn how incentives succeed (or fail), how resources get allocated, and what sort of obstacles prevent people from getting those resources, whether they are concrete (like food and transportation) or more aspirational (like education and love).

The fact is that solving problem is hard. If a given problem still exists, you can bet that a lot of people have already come along and failed to solve it. Easy problems evaporate; it is the hard ones that linger. Furthermore, it takes a lot of time to track down, organize, and analyze the data to answer one small question well.

Knowing what to measure, and how to measure it, can make a complicated world less so.

Los datos no mienten: una prostituta callejera de Chicago tiene más probabilidades de practicar el sexo con un policía que de ser detenida por uno.

Anyway, this is just the latest example of why I never trust statistics I get from people in the field of medicine, ever.

Steven D. Levitt

Married people, for instance, are demonstrably happier than single people; does this mean that marriage causes happiness? Not necessarily. The data suggest that happy people are more likely to get married in the first place. As one researcher memorably put it, "If you're grumpy, who the hell wants to marry you?

Gut hunches are routinely passed off as dogma while conventional wisdom flourishes even when there is no data to back it up.

The fact is that solving problems is hard. If a given problem still exists, you can bet that a lot of people have already come along and failed to solve it. Easy problems evaporate; it is the hard ones that linger. Furthermore, it takes a lot of time to track down, organize, and analyze the data to answer even one small question well.

There is nothing like the sheer power of numbers to scrub away layers of confusion and contradiction.

Gun murders are down? Well, you figure, that must be from all those tough new gun laws—until you examine the data and find that most people who commit crimes with guns are almost entirely unaffected by current gun laws.