There are two types of validity and one type of reliability that denotes well- conducted researches (Jacobsen, 2009 p 417). These make sure that it actually measures what being expected (i.e. internal validity), it can be generalized and transformed to other areas (i.e. external validity) and that it is accurate and trustworthy (i.e. reliable).
Internal Validity
One question that can be asked is if the indicators that’s being used, actually measures what’s of interest. Such critical considerations should be used during the entire process. (Jacobsen, 2009)
External Validity
A central element in both quantitative and qualitative approaches is that the investigations cover a sample of a population. However, in a quantitative approach, if the selection of the sample is performed properly, a generalization of the sample can be made to the whole population with a degree of uncertainty. The degree of uncertainty means that a level of vagueness must be considered when a generalization is made from a sample to a whole population. (Jacobsen, 2009) A low response rate would for example imply a higher degree of uncertainty in terms of a generalization.
Reliable Results
Another question, which is considered a must, is if the way the research is performed has an influence of the outcome of the results, in other words, if the research approach has an impact of the results. (Jacobsen, 2009)
How the study was performed
It is apparent that the quantitative and qualitative research methods both have their advantages and limitations. And since qualitative research increase internal validity and quantitative improve external validity (Kotzab et al., 2005), a combined approach was used in this study, but with more focus on a qualitative approach.
In the qualitative method, five companies were chosen for more in depth research via interviews. Two of them are current customers of Consafe Logistics, the other three are companies that are currently using the SCOR
model. All firms have knowledge about performance measurement and are operating one or several warehouses. All five companies have been chosen due to their interest in this study and performance measurement in general. However, the results cannot be generalized for the same reason, since qualitative methods do not give indications about general nor typical aspects, but rather about characteristics that are special and unique (Jacobsen, 2009). That is why a mixed quantitative and qualitative web-based survey was selected to follow up on the qualitative interviews.
The web-based survey was sent to all of Consafe Logistics customers. In this way was possible to see if there were an indication of connection between the initial five companies and a wider range of customers, which was represented by a sample of the customers. The analysis focused on finding gaps between what’s currently being measured by customers, thus concentration was essentially directed on the first, broadest and mandatory question in the survey, which also obtained most responses. More specifically, the focus was on what types of metrics are being used by customers today and how can they be translated to a standardization based on the SCOR model.
Indication of validity and reliability
The pre-study made it possible to outline what questions were of interest to ask in the web-based survey, i.e. for the authors to ensure that the questions that follows from the result of the interviews, actually would measure what’s of interest (i.e. internal validity). A session with the authors’ supervisor at Consafe Logistics and a colleague was also conducted to ensure internal validity, and the web-based survey led to the basis for analysis of research questions 1 and partly research question 2.
Furthermore, the sample of companies in the interviews, which are operating in warehousing, performance management and some using the SCOR model, as well as the sample of customers and their metrics from the survey that could be translated into an equivalent to SCOR, are considered to be representative for the generalization of the results of this research (i.e. external validity). Thereby the results could be applied to Consafe Logistics’ warehousing services.
In terms of reliability, the qualitative interviews were designed after the same template of questions related to performance measurement, but also SCOR and warehousing. In addition, supervision from Jan Olhager, Professor in Supply Chain Strategy, as well as discussions and a workshop with Lars Magnusson, member of the board of directors at SCC, strengthens the reliability of this thesis due to their knowledge in research writing and knowledge of how to use the SCOR model.
To summarize, the pre study made sure that a reliable investigation could be made (since it confirmed that theory found in literature was the case also in reality) and the web-based survey ensured that the results could be generalized to a broader customer base, even though the response rate (17.4%) needs to be questioned. Guidance from the authors’ supervisors at Lund University and at Consafe Logistics, as well as supervision from the board of directors at SCC also supports the trustworthiness of this report. The study thereby measured what was of interest (internal validity), and since the web-based survey was re- sent two times to the customers no further generalization could be made in the way this thesis was carried out (external validity).
Source criticism
Even though all sources in this thesis have been selected with care and interest to fulfill the purpose, there is always a need to be critical. Source criticism means that the writers take a critical perspective of the sources that have been selected, as well as how the collection of data has been conducted. By doing so, the authors should ask themselves if the result would have been different if alternative ways to conduct the research had been selected. (Björklund & Paulsson, 2003)
The literature was selected from well established and reviewed sources, and focus has been directed towards finding influential literature. For the empirical data the authors have found the people that have taken part of this research reliable and knowledgably. The results of the study may have become different if other sources would have been used. To make this investigation as reliable as possible the authors have taken this into consideration and possible actions to reduce that risk have been taken, for example by using a combined quantitative and qualitative approach, even though more focus has been on the qualitative.
3
R
ELATED
L
ITERATURE
Three areas were chosen for research in this study, performance measurement, warehouse management and the SCOR model. The studies together provided the knowledge necessary to conduct the empirical data collection, and consequently develop the performance measurement system.
Performance measurement, will give the reader a brief insight to the importance of performance management and performance measurement. This study was conducted to find a method that would help when developing a performance measurement system.
Warehouse management, explains the meaning of warehousing operations, warehouse management and warehouse management systems (WMS). It summarizes general warehouse processes, warehouse types, warehouse trade- offs, trends and challenges. The purpose was to provide an understanding about warehousing, CL’s services and products as well as the industry as a whole for which the scope of this thesis’ is carried out. Furthermore, the chapter gives an understanding of the classification of metrics in warehousing, thereby it also works as a basis for the survey as well as the analysis.
The SCOR model will provide an introduction to the SCOR model and SCOR methodology. The purpose is to include enough information about the SCOR model so that the developed performance measurement system can be understood.
The Venn diagram in Figure 4 shows an idea of how the theory in this study is connected.
Performance measurement
The SCOR model
Warehouse management