Many consumers rely on specifications such as pixel counts or carats to make purchase decisions without fully understanding what they represent or how useful they will be, suggests a new study that will appear in the Journal of Consumer Research.

Consumers that get caught up with numbers may end up breaking their budget or overlooking other features that may be more useful to them, said lead researcher Christopher K. Hsee, a professor of behavioural sciences and marketing at the University of Chicago.

For example, consumers may not understand the value of ISO rating on print film, pixel counts for digital cameras, output wattage for amplifiers or the number of carats in a diamond, but they tend to value these specifications over more tangible qualities, the study said.

"The pursuit of numbers … entails its costs and can lower overall consumer welfare," the study said. "To pursue numbers, consumers may spend too much money or otherwise sacrifice other benefits."

Researchers conducted five experiments, asking participants to select between products that were presented with differing amounts of specifications. The study found that in all trials, the majority of participants opted for products that were presented with the most quantitative specifications.

One trial asked participants to choose between equivalent digital cameras. The study found about 75 per cent of participants opted for cameras that were presented as having a higher resolution.

"The first thing many digital camera buyers consider is megapixels," the study said. "In reality, beyond a certain threshold [around two megapixels], the resolution [sharpness] of a digital camera, for most amateur consumers, matters little to their experiences, and other features, such as portability and image vividness, become relatively more important. Yet the presence of specifications such as the megapixel ratings leads consumers to pursue megapixels by spending extra money or by sacrificing other features."

The study suggested that in some cases consumers may favour products with specifications, such as the number of carats in a diamond, because it provides them with bragging rights.

"Although a two-carat diamond may not look much better than a one-carat diamond, the fact that one owns a two-carat diamond is a source of admiration from others and happiness within oneself," the study said.

Assess products based on usage, study suggests

The researchers noted that in some instances, specifications can be helpful.

For example, knowing calorie counts of food items may be a useful determinant for someone on a diet.

The study suggests consumers should assess products such as digital cameras on how they will use them in their daily lives.

For example, they might ask to see a set of camera prints and should use them as a starting point to develop a complete impression of the camera before moving on and evaluating a second potential camera.

The study will be published in the April 2009 edition of the Journal of Consumer Research.