# Statistical Tolerance Analysis--A Survey on Awareness, Use and Need in German Industry
## 4 The Survey--Implementation, Questionnaire and Participants  
The common objective of methods of information acquisition and data collection is to enable empirically founded statements that can be generalized [50]. The methodical and systematic collection of data is assigned to social research and differentiated into qualitative and quantitative social research. While qualitative social research primarily aims at the subjective and thus hidden meaning of the topics from the participants' point of view, quantitative social research captures the objective meaning of the topics questioned [50]. This quantitative evaluation allows the direct derivation of key indicators and thus absolute findings from the clearly assignable responses of the participants. Thus, the findings are objectified, and conclusions of general validity can be drawn. With the aim of generalizing knowledge and generally valid formulation as well as an objective review of hypotheses, quantitative social research was thus applied in the data collection. This ensures the desired representativeness and objectivity of the results [51].  
The collection of data usually takes place via questions in a questionnaire, which are answered by randomly selected participants of a specific group personally, by telephone, in writing or online [50,52]. In our work, a compilation of 35 open questions (allowing answers as free text) and closed questions (single-choice or multiple-choice from given answers) [53] was established and assigned to the following four subjects of the questionnaire:* General information on the participant;
* Significance of deviation effects on the aesthetic and functional quality of products;
* Approaches to take deviations into account as well as to reduce their effects on products at an early stage;
* Current state of use of tolerance simulations and future potential.  
Subsequently, the questionnaire (in the form of an interactive PDF) was sent by e-mail in July and August 2012 to 381 participants from German mechanical engineering companies with the request to participate in the data collection. Finally, 102 participants completed the questionnaire and returned it via e-mail. This was a response rate of about 27%, which exceeds the usual response rates for online surveys of 5% to 20% [54]. Furthermore, the number of 102 returned questionnaires corresponds almost exactly to the recommendation to use at least 30 and ideally 100 data sets for representative online surveys [55]. The data collected in this study are thus representative and can be evaluated and discussed in the following. Figure 1 shows the number of questionnaires sent out and the number of returns per federal state. The complete interactive questionnaire (in German) is available from the corresponding author.  
The survey participants came from various companies in the German mechanical engineering industry. This showed a balanced distribution of participants in terms of the size of their companies. Small and micro enterprises (<50 employees) made up the majority compared to medium-sized businesses (50 to 250 employees) and large companies (>250 employees). Figure 2 shows the distribution of participants among the four types of companies depending on the size of the company (in employees), which follows the company definition of the European Union [56].  
The majority (52%) of the 102 participants worked in the engineering design department. The focus of the work of other participants was in management (15.7%), quality management (10.8%), research and development (8.8%) and production (7.8%). The composition of the participants thus reflected the diversity of Germany's mechanical engineering industry, both in their responsibilities and in company size.  
Figure 1: Distribution of questionnaires sent (**left**) and returned (**right**) by the 16 federal states of Germany.