CAPÍTULO III: MEDIDAS DE SEGURIDAD EN LOS CENTROS ESPECÍFICOS DE
1. DISPOSICIÓN GENERAL SOBRE LAS MEDIDAS DE SEGURIDAD
A paper version o f the computer survey is presented in Appendix 1. This was an integrated survey focusing on the SP-choice experiment, but other com plementary information and methods are included. Considering that this would be a novel experiment for valuing quiet/noise it was aimed to test a wide range o f variables (socio-economic, attitudinal, behavioural, etc.) on the marginal valuations.
The structure o f the survey is represented in Table 4.4. Questions are grouped by type but their order in the survey were placed such that more difficult (less acceptable) questions were placed later (e.g. information on household income levels), and giving priority to the SP-choice part and necessary input information. The survey aimed to integrate the possible influential variables that were found to affect community reaction to traffic noise (see subsection 4.3.2). The initial part o f the questionnaire (codification o f block and apartment) is prepared in advance to each interview, having information o f each apartment layout. I he questionnaire started with an introduction to the research study and warm-up questions. In order to avoid possible strategic bias the respondent was told that the survey was about environmental attributes in the residential area. By the time the SP-choice experiment was shown to respondents, the respondents were already supposed to be familiar with the environmental attributes (gathering o f the RP information on housing choices had already occurred, as well as the rating o f the attributes). This would help to construct a realistic market for valuing quiet/noise when individuals are indoors.
Com plem entary questions on perceptions o f noise during the day and night and annoyance were placed in the last part o f the survey. In this study, annoyance variables were tested as possible influential variables in the marginal values o f quiet/noise. Questions about age, educational level, household net income were placed at the end o f the interview since these
can be considered more personal questions and hence affect the acceptability o f the survey it placed at the start.
Table 4.4: Structure of the Com puter Survey.
Components Variables
Socio-economic information o f the household (respondent and members): sex, age, number o f people by household and living num ber o f parking spaces ; ratings for view, sunlight, noise.
APARTM ENT
Num ber o f years living at the current apartment.
LIFE STYLE Num ber o f hours spent at home on average during the day (7 am-10pm); most usual place in the home for staying; Most usual activities conducted when indoors; if normally work/study over the weekend and/or stays home.
If household members suffer any noise-related health effects (list).
Day-time and night-time noise levels (ratings); most important cause o f disturbance indoors; how noise interferes with 1 intended activities; How much annoyed (ratings).
4.5.1 Com plem entary Valuation M ethods to the SP-choice
This research is centered on the SP-choice m ethod for valuing quiet/noise. The SP experimental design as set requires time for respondents to think and decide, especially in
rating attributes (view, noise, sunlight) in four apartment situations and assessment o f the twelve binary choices.
The use o f other complementary valuation approaches should not constrain the acceptability o f the survey by increasing substantially the duration o f each interview. Therefore, it was decided to gather data on the Revealed Preference o f housing purchases made by the same respondents. Because apartment purchases were made some time ago, the respondent was also asked to consider a choice “now ” (i.e. at the moment the survey was conducted) assuming the same choice set as before (ex ante RP choice). The RP approach (ex ante and ex p o st choice) is discussed in chapter 8 in detail.
Considering that the contingent valuation method is a simple case o f the SP approach (see also chapter 2), this study aimed to test the open-ended elicitation format using as a frame o f reference the individual’s perceptions o f the levels o f quiet/noise in the same apartment situations (one single situation was then offered to each respondent, considering either an improvement or deterioration in the levels or both). The design o f the W TP questions is discussed in chapter 9 in more detail. These methods would allow the comparison o f values, and assess their possible convergence or divergence.
4.6 CONCLUSIONS
One o f the interesting features o f the computer survey was to explore respondent’s experience with the levels o f the attributes at the current apartment, and his/her familiarity in other situations (not necessarily) experienced in the same block or lot. This conveyed a greater level o f realism in the SP experiment. This fact was expected to minimize the hypothetical bias. Whereas the use o f respondent’s perceptions is not new in choice experiments, the link o f the “perceived stim uli” with apartment situations fronting the main road and at the quieter fa?ade and with lower - upper floors was novel in simulating a real market experiment involving apartment purchases.
Kihlman (2 0 0 1) pointed out the importance o f dwellings in noisy areas having at least a quieter fa9ade in order to be able to solve “the city noise problem” . Situations involving front-back situations represent much higher variation in the physical noise levels than along the same facade o f the respondent.
Having received contributions from different disciplines, the survey integrated a wide range o f variables related to the household and the situation in the block and exposure to main road, such as socio-economic, behaviour when indoors and towards averting noise, perceptions and attitudes. These would serve as test variables when assessing the major determinants o f individual’s preferences for quiet when indoors. Complementary valuation methods were devised: the revealed preference information on actual choices (choices ex ante and ex post) and willingness-to-pay questions. These constituted a compromise between the duration o f the survey (not to affect respondent’s acceptability) and use o f information (links with SP-part).