The 2013 yearbook includes a selection of the most relevant CIS barometers over the year. The section on “Perceptions of the economic and political situation” presents the common questions of the different barometers on this subject, from both retrospective and prospective points of view. In the section on “Assessment of the government and the opposition”, the interviewee's assessments of the government, the opposition, the Ministers and main political leaders can be reviewed in the political barometers applied every three months. The other sections represent a selection of the questions of each monthly monographic study. For this, an equilibrium was sought between the relevance of each indicator and the number of questions chosen in that month. However, sometimes the selection of some sets of questions has required more space.

The presentation of the data referring to each question is intended to maintain a similar structure to that within each section. Therefore, the blocks devoted to “Perceptions of the economic and political situation”, and “Assessment of the government and the opposition”, incorporate the longitudinal annual evolution of these opinions with a graph representing the monthly or quarterly responses. Meanwhile, the monthly themed blocks show the marginal frequencies (or average frequencies, depending on the case) for each of the selected questions, also accompanied by a specific graph. In most cases, these graphs represent the percentage of each response option on a scale of 10 or out of 100%, depending on the case. However, for some specific questions, such as the average assessment of political leaders and Ministers, this representation is adjusted to fit closer upper and lower limit values for clarity, given the low variation in these values.

Representative names have been given to the content of the presented tables and to the month or themed block to which they belong, to make them easy to identify. In this way, for example, the first table referring to the block of “Perceptions of the economic and political situation” is called “Table SIT1”, the first table for the block “Assessment of the government and the opposition” is identified as “Table POL1”, the first table of the barometer for February is called “Table F1”, and the tables of the poll on public opinion and fiscal policy are identified as “Table FIS1”.

Next, cross-references are provided with the most commonly used socio-demographic and political indicators the CIS offers its users: gender, age, marital status, education, occupation, social class, ideology, voting history, religion and locality. Some of these variables have been recoded or transformed to make it easier to read and interpret the data which are generally calculated for each category of that variable (in percentage rows). In a few questions only, these percentages are calculated by columns, as indicated in the document.

The variables of age and social class maintain the same categories provided by the CIS for the different studies through its website. However, ideology, locality, voting history and education have been recoded differently to present a more synthesised table of results.

Age includes the following intervals: “Up to 24”, “Aged 25 to 34”, “Aged 35 to 44”, “Aged 45 to 54”, “Aged 55 to 64” and “65 and over”. In the ideology variable, the more extreme values are grouped, the left represented by the values “1-2”, “3-4”, and the right by the values “7-8” and “9-10”. The intermediate values “5” and “6” have been kept ungrouped. The categories of locality size have been identified as follows: municipalities of fewer than 10,000 inhabitants are classified as “Village or small town”, of 10,001 to 100,000 inhabitants as “Town”, of 100,001 to 1,000,000 inhabitants as “City”, and more than 1,000,000 inhabitants as “Metropolitan area”.

A combination of questions were used to create the variables of education, social class and religion. In the case of education, the question of whether they went to school is combined with the question measuring the highest level of education taken. This is used to create six categories: “Primary or less”, “Early Secondary”, “Mid-level VT”, “Later Secondary”, “Upper-level VT”, and “University”. The new variable of religion combines the definition of religion with the frequency of religious practice, creating three categories: “Practising believer”, “Non-practising believer”, and “Atheist, non-believer”. In voting history, the question of whether they voted in the last elections is combined with the question of which party they voted for. The following categories were created: “PP”, “PSOE”, “IU/ICV”, “UPyD”, “CiU”, “Other parties”, “Was not old enough”, “Blank vote”, “Did not vote”, “Does not remember”, and “N/A”. The category “Did not vote” includes all the options reflecting abstention in either of the two original questions, and invalid ballots.

Meanwhile, the social class variable was created based on the responses of interviewees to three questions: employment status, occupation and socio-economic status. The five categories in this variable are: “Upper/upper-middle class” (groups professionals, qualified technicians, senior and middle management), “New middle classes” (Non-manual salaried workers), “Old middle classes” (business owners, the self-employed and farmers), “Skilled workers” (skilled manual workers, supervisors and craftsmen/women), “Unskilled workers” (workers in industry and services, and agricultural labourers).

The answer categories “Don't know (D/K)” and “No answer (N/A)” of the cross-referenced explanatory variables are presented in the tables only in cases where the figure is significant and that option is representative. Thus D/K and N/A have been kept in the presentation of political ideology, voting history and religion, but not in the other cases. Meanwhile, if included in the design of the questionnaire, it is specified whether a response is a “Spontaneous Response” contributed by the interviewee when asked the question, and on other occasions, if the category was one that the interviewer was instructed not to offer as a pre-set response option, in which case “DO NOT READ” appears next to it.

The fact that some of the categories of the different indicators are not frequently found among the answers given by interviewees makes it necessary in this section to highlight the limitation of interpreting the percentages in these cases. For this reason, the number of people (n) that respond per category or as a whole to those questions is shown in brackets.

Sometimes partial information is provided about certain questions to make them less complicated to read. For example, in a set of questions with the following response options: a lot, some, not much or not at all, used to capture a frequency or a degree of agreement, the options "a lot + some" have been grouped for presentation in the table. There is a single exception linked to this type of questions, in data referring to the fiscal barometer, where the “not much” group has been selected, given the frequency of other categories. Meanwhile, in questions which include the possibility of mentioning more than one answer (for example, in first and second place), only the data referring to first place are represented for most of them. Moreover, in the case of questions with a scale of 0 to 10, when not in a set of questions, the categories are grouped to simplify reading: “0-2”, “3-4”, “5”, “6-7” and “8-10”.

Throughout the document there are questions labelled “Multi-response” which aggregate the possible responses from interviewees into a single list of options or values. These questions have the characteristic in which (n) represents the total answers, unlike in the other questions, rather than the total number of people responding.