The Decision-Making Process for Buying a Car

When you want to buy a new car, the decision is often not easy. Rational and emotional arguments can contradict each other. Which is the right way?

What is important when deciding on a car?

When we want to buy a new car, we first look at the various options (alternatives). We look around on the road and see many models. First we take the 3 or 5 models that we like best.

But then it gets complicated. How do we decide which of the models is the best choice for us? For this we need criteria that we want to use to evaluate the different models.

Quantitative Criteria

First, there are criteria that we can measure, look up or specify directly. So we first collect the data for each of the models that we include in the decision.

Here are some examples:

Price

Price is at the top of the list when making a selection. But the price is not everything, because it can also be a little more or less if the object of desire fits perfectly.

The price is a number, the lower the better.

Costs

What will the running costs of the car be? This value will not be easy to quantify. So we use a scale here to estimate.

This criterion can use “Likert-4” as an attribute.

4 levels from “good” to “bad” are queried.

Consumption

Fuel or electricity consumption is an important criterion.

Consumption is a decimal number, the lower it is, the better.

Performance

The performance in horsepower or kilowatts often plays a role, as does the next criterion.

Power is a number, the higher the better.

Qualitative Criteria

And where is the gut feeling? If the quantitative (measurable) criteria speak in favor of a certain model, it is possible that another option is the better one.

In this case, there is the pairwise comparison. We determine a criterion - comfort, for example - and always compare two options with each other. So, for example, model A is more comfortable than model B - but model B is not as comfortable as model A.

This pairwise comparison is then carried out for all (quantitative) criteria. This can be quite a lot of work, depending on how many options and criteria are to be used.

Convenience

Clearly a criterion that cannot be quantified.

This criterion is best suited to the “Analytical hierarchy” attribute.

Quality

For the quality to be evaluated, a number could certainly be determined with a lot of work by determining and comparing the workshop data of the options. However, this is a lot of work and we usually know “roughly” which model is better or worse in terms of quality.

The “Analytical hierarchy” attribute is also best suited for quality.

Image

The image of a vehicle is certainly the most qualitative criterion. It is not only related to the personal opinion of the decision maker, but also refers to the group of people in front of whom the image is to be evaluated.

It could hardly be softer or more uncertain.

The image can only be evaluated with the attribute “Analytical Hierarchy”.

The Rating

Once all the options and criteria have been collected, the decision is ready for the evaluation of the criteria. At this point, we have already done most of the work, because thinking about which criteria and options to use is real mental work.

Both sides of the medal

Quantitative evaluation

We then use the values determined for all criteria. So price, consumption and everything else. That’s easy.

Then two further factors come into play:

• Prioritization
• Distribution

With priorization, we specify which criteria are particularly important to us - these are at the top - or which are less important to us - these are at the bottom.

Distribution is about how the “effectiveness” of the priorities is distributed. The simplest form is equal distribution. This means that all priorities are weighted equally. However, this does not have to be the case. Other distributions are also conceivable:

• Linear, i.e. evenly
• Stepped
• Square, strongly increasing
• Negative square
• Individual - entered manually for each criterion

Qualitative evaluation

This is not readily possible for the qualitative evaluation. This is why we also use the pairwise comparison to determine a priority.

However, here we no longer compare the models, but the criteria. For example: Comfort is considerably more important than image. Or quality is slightly more important than comfort.

And where is the distribution? Well - in the pairwise comparison, each query not only asks for “better” or “worse”, but this question also allows a gradation.

• A is a little better than B
• A is slightly better than B
• A is better than B
• A is much better than B
• A is extremely better than B

These two pieces of information make it possible to calculate the decision for one of the options (using the so-called analytical hierarchy).

The Decision

So at the end of the calculation, we have two values, one from the qualitative, number-based decision - and another calculated from the pairwise comparisons.

This is a kind of dilemma, as we know it from many situations in everyday life. Head or gut - that’s the short form of this problem.

If we want to make things simple, we split the two sides in half. 50% of one side and 50% of the other side then gives us a number for each option. For the more advanced, we can shift this ratio in either direction as a test. Then the gut or the head wins. And often both sides of the coin produce the same result.