5.4.1 The questionnaire and response
A questionnaire was used to measure tenants’ perceptions of the importance of maintenance services, and tenants’ satisfaction with various maintenance services. This questionnaire was sent to tenants in the Netherlands who live in social rented housing. Other clients of housing associations, such as home owners who enjoy the technical services of housing associations, were not included in the sample. The sample consisted of respondents who are cus- tomers (i.e. tenants) of four main Dutch housing associations located in cen- tral and western areas of the Netherlands, namely: Vivare, Portaal, Vestia, and Staedion. The questionnaires were distributed in February 2006. This distribu- tion was preceded in December 2005 by a pilot study. Table 5.1 sets out the key characteristics of the four housing associations.
Approximately 28,000 questionnaires were sent to potential respondents, and more than 6,000 respondents participated by returning the questionnaire. This amounts to a response rate of 22%. Reminders were not sent, since the response rate was higher than we had expected (20% response). Respondents could either fill in the questionnaire on paper or online. 5.6% responded on- line and 94.4% responded in writing, and the results of both groups are highly comparable. As far as the characteristics of respondents are concerned, we can conclude that the online respondents were, on average, almost ten years younger than respondents who filled in the paper version of the question- naire, and fewer of them were retired. Moreover, in the case of online re- spondents, 64% were male (compared with 47% male overall), and they tend- ed to be more highly educated.
The attributes – the maintenance services – were determined by examining the literature (see e.g. Straub, 2001; Thomas et al., 2005), and by asking experts as well as tenants for their opinions. Only attributes that might have some impact on residential satisfaction were included. For example, construction work without any aesthetic, functional or other impact that might directly in- fluence tenant satisfaction was not included (see Table 5.2 for a description of the specific maintenance services).
The levels of importance of and satisfaction with each of these attributes were then evaluated using the large-scale survey described above. Respond- ents’ perceptions of the importance of the various maintenance services were measured on a seven-point scale, ranging from (1) ‘extremely unimportant’, through (4) ‘neither important nor unimportant’, to (7) ‘extremely important’. The levels of satisfaction were also measured on a seven-point scale, ranging from (1) ‘extremely dissatisfied’, through (4) ‘neither satisfied nor dissatisfied’, to (7) ‘extremely satisfied’.
their dwelling by asking: ‘How do you experience the current maintenance of your dwelling?’ Seven categories of answers were provided, ranging from (1) ‘extremely negative’, through (4) ‘neither negative nor positive’, to (7) ‘ex- tremely positive’.
A pre-test was conducted in two phases. First, the survey instrument was pre-tested by ten purchasing and technical management professionals to ensure content validity. These practicing managers read, checked and made recommendations for changes to the survey in a group meeting and a small number of separate meetings. According to the recommendations, some questions were rephrased to improve validity and clarity. Second, the ques- tionnaire was sent to 613 potential respondents, all customers of the Stae- dion housing association who lived in the ‘Lamel’ housing block in The Hague. A total of 116 questionnaires were returned. When these were evaluated, spe- cial attention was paid to the difficulties experienced by respondents when filling in the questionnaire (see Appendix 2 for the questionnaire).
5.4.2 Regression analyses
Regression analyses must be conducted under certain conditions. First of all, the predictors must be linearly independent, i.e. one must not be able to ex- press any predictor as a linear combination of the others. This condition tells us that the correlations between the independent variables should not be too high. While it continues to be a point of debate for statisticians, a commonly accepted (although somewhat strict) rating is 0.65. In this research, we as- sume that a score higher than 0.65 may suggest multicollinearity problems. The individual effects of variables that are connected too closely to one an- other cannot be distinguished any more.
For single-family dwellings, only maintenance of toilets and maintenance of kitchens correlate with a rating higher than 0.65, namely 0.671. For multi- family dwellings, two pairs of attributes correlate with a rating higher than 0.65. Again, maintenance of toilets and maintenance of kitchens, rate 0.671. In addition, cleaning of shared areas and maintenance of porches, galleries, corridors and communal staircases correlate with 0.833. Therefore, mainte- nance of toilets has been left out of the regression analyses for both single and multi-family dwellings. Cleaning of shared areas has been dropped from
Table 5.1 Key figures of the housing associations included in the research (consolidated figures)
Staedion Portaal Vivare Vestia
Housing units 32,472 53,969 23,539 71,618
Balance sheet value €1,379,802,000 €1,893,785,000 €730,404,000 €3,231,000,000
Employment 388 534 298 915
Local departments 5 5 5 13
Core region of activity The Hague Amersfoort/Utrecht, Arnhem/Nijmegen, Leiden
Arnhem area Southern Randstad Sources: Annual reports Staedion (2007), Portaal (2007), Vivare (2007), Vestia (2007); data December 31st, 2006
the regression analysis concerning multi-family dwellings.
Another requirement for conducting regression analyses concerns the nor- mal distribution of variables. This is not the case for the collected data. In ac- cordance with the Central Limit Theorem, however, the sample used for this research is large enough to assume that the sample mean scores resemble the mean scores for the population as a whole.
Given the exploratory character of this research, the enter-method for con- ducting regression analyses was used.
5.4.3 Missing data
The need for maintenance services depends, in the first place, on the type of dwelling. The housing stock can be most obviously broken down into single- and multi-family dwellings. Some maintenance services, such as lift main- tenance, can only be delivered to tenants of multi-family dwellings. For this reason, the analyses were conducted separately for single- and multi-family dwellings. However, not all multi-family buildings have features such as lifts and balconies, meaning that missing values appear for such services – some- thing that is termed Not Missing At Random (NMAR). NMAR refers to miss- ing observations related to the outcome of interest. The regression analyses have only been conducted for cases that include all answers on the related (satisfaction) questions. Therefore in the regression analyses, in particular for multi-family dwellings, N is limited compared with the overall response.