How your affinity with the parties is calculated

This test belongs to a family of tools known as political affinity tests or voting advice applications. The idea is always the same: gather the parties' positions on a series of issues, ask for your opinion on the same issues and measure how far you are from each one.

It is worth being clear about what it is not. A poll asks a representative sample in order to find out what the population as a whole thinks or how it will vote. This test extrapolates nothing: it only tells you how far you are from each party. The result is neither a forecast nor a voting recommendation. Why the barometer, which gathers the answers of people who take the test, is not a poll either is explained in "Why the barometer is not a poll".

Why counting agreements is not enough

The simplest approach would be to count on how many questions you agree with each party. But that would treat two very different situations the same way: a one-point gap (you "strongly agree" and the party "agrees") and a four-point gap (you at one end of the scale and the party at the other).

So the test makes three corrections. The first penalises large gaps more. The second gives more weight to your firm opinions than to moderate ones. The third, in the full test only, takes into account how much each topic matters to you.

The calculation, question by question

For each statement you answer:

Step 1. The gap. The party's position (1 to 5) is subtracted from your answer (1 to 5) and the absolute value is taken. The result ranges from 0 to 4.

Step 2. The base score. It is (4 − gap)². Because it is squared, each extra point of gap costs more than the previous one:

Note the jump: a single point of gap already costs almost half the score.

Step 3. The conviction factor. It is 0.5 + (distance from the center × 0.25). If you answer at one end of the scale ("strongly agree" or "strongly disagree"), it is 1; if you answer "agree" or "disagree", 0.75; if you stay at "neutral", 0.5. A neutral answer weighs half as much as a firm one, and a moderate one three quarters.

Step 4. The weight. The confidence weight of the party's position (currently 3 for all of them, including estimated ones) is multiplied by the importance you give the topic (from 1, "not at all", to 5, "a lot", in the full test; always 3 in the quick test) and by the conviction factor.

Step 5. The percentage. For each party, the points from all questions (base score × weight) are added up and divided by the maximum it could have obtained. That ratio, multiplied by one hundred and rounded to one decimal place, is your affinity.

A real example

Take the statement "Pretrial detention should always be decided by a judge, case by case, and not applied automatically depending on the offence." Article 19 of the Constitution lists the offences for which pretrial detention applies automatically, and the Chamber of Deputies voted to extend that list in November 2024. Suppose you answer 4, agree, and give it an importance of 4 ("quite a lot").

Your conviction factor is 0.75, because you are one step from the center. The weight is 9 for every party (confidence 3 × importance 4 × conviction 0.75), and the maximum on this question is 16 × 9 = 144 points.

Had you answered 5, strongly agree, the conviction factor would be 1, the weight 12 and the maximum 192. The order would change: SOMOS, which proposes repealing mandatory pretrial detention, 100%; PAZ, Movimiento Ciudadano, the PRI and the PAN, 56.3%; Morena, the PT and the PVEM, 0%. The same opinion, expressed more firmly, separates the parties more and weighs more in your result.

All eight positions in this example are documented, and their sources are listed at the end of this analysis. Those of Morena, the PT, the PVEM, Movimiento Ciudadano and the PAN come from their groups' votes in the Chamber of Deputies on 13 November 2024; the PRI's from its 2024 platform (its group also voted against), and those of SOMOS and PAZ, parties registered in 2026 with no deputies, from their programs of action. When the parties file their 2027 platforms, in the first half of January, we will review the positions, as the methodology explains.

Two questions together

Points add up across all questions: that is why the final percentage is not "the share of questions on which I agreed with the party". Let us add a second statement to the previous answer, one that only appears in the full test: "The government should use facial recognition cameras and artificial intelligence to prevent crime." You answer 5, strongly agree, but this topic matters only a little to you (importance 2). The conviction factor is 1, the weight 3 × 2 × 1 = 6 and the maximum 16 × 6 = 96 points. With the first question, the total maximum is 144 + 96 = 240.

The PVEM, whose 2024 platform proposes using "facial recognition cameras" and artificial intelligence to prevent crime, matches you exactly on the second question, and still only reaches 43.8%: its match is on the question that matters less to you, and on the other it is three points away. The PRI and the PAN match you on the first and are two points away on the second; PAZ and Movimiento Ciudadano are one point away, and that is why they come out ahead. SOMOS and the PVEM tie by opposite routes. We have checked these figures with the same code that calculates the test result.

The quick test and the full test

The full test has 45 statements, and for each one you can mark how much the topic matters to you, from 1 ("not at all") to 5 ("a lot"); if you leave it, it counts as 3. The quick test has 20, and importance is 3 for all of them: only the gap and conviction count. Otherwise, the calculation is identical.

The eight nationally registered parties are all included in the calculation. Each has a position on every statement; of the 480 positions in the database (60 statements, including the tiebreak ones), 346 link to the document they come from and the other 134 are marked as estimated on the party's page. In the calculation they all carry the same weight. Your age, your sex and the party you would vote for, if you choose to give them, have no effect on the result.

Topic by topic, and the compass

Your result also shows your affinity with the parties on each topic. It is calculated with the same formula, but only with that topic's statements: if, for example, you answered the four on security, that topic's percentage is based on them alone and on the importance you gave them.

The political compass is calculated differently. It does not compare your answers with the parties' positions: it turns each answer into a number from −100 to +100, according to the direction in which the statement pushes, and averages them on each axis. Neither importance nor the conviction factor plays a part, and the statements on security, justice, elections and institutions do not count: 29 of the 45 statements move the compass. That is why the party you have the highest affinity with is not necessarily the one closest to you on the compass: your affinity takes all 45 statements into account, the compass only 29. How the direction of each statement is set is explained in "Who is on the left and who is on the right of the compass".

Three practical consequences

Answering "neutral" is not neutral. It halves the weight of the question: you give up half of its ability to tell the parties apart. If you have an opinion, say so.

Skipping a question is perfectly fine. Questions you do not answer ("Don't know / Skip") are left out of both the top and the bottom of the division: they do not count as a disagreement. The same would happen if a party had no position on a question.

Ties make sense. If two parties hold the same position on almost every statement where you took a side, their percentages will be very close. This is not a flaw in the calculation: on those issues, they are alike. That is why the test has 15 tiebreak questions, which are not part of the main test. If the second or third party in your result is 3 points or less behind the first, the test offers you up to 8: those that best separate the tied parties. Only questions on which all the tied parties have a sourced position (never an estimated one) are used, and only if at least one separates them by 2 points or more. Your answers are added to the usual calculation for all parties, with importance 3. You can only break a tie once, and it does not change your compass. The details are in the methodology.

What this number does not measure

It does not measure whether a party keeps its promises: the positions come from its documents, votes and statements, not from an assessment of its record. Nor does it measure how much you trust its candidates or its ability to get its proposals through, which depends on how many deputies it wins and whom it allies with. And the test compares your ideas with those of the parties, not with each candidacy: in your district you choose a specific person, and in 2027 some parties will run in coalition. How the 500 seats are allocated is explained in "How the 500 deputies are elected", and the calendar in the 2027 election guide.

If you find a position that seems wrongly assigned, the methodology explains how to let us know. We check it against its source and correct it if necessary. To see your own result, take the test.