Bass diffusion models are one of the competing paradigms to forecast the diffusion of innovative products or technologies. This approach posits that diffusion patterns can be modeled through two mechanisms: Innovators adopt the new product and imitators purchase the new product when getting in contact with existing users. Crucial for the implementation of the method are the values assigned to the two parameters, usually referred to as p and q, which mathematically describe innovation and imitation mechanisms. The present paper is based on the findings of a research project about policy measures to promote the diffusion of Electric Vehicles in Germany. It investigates how practitioners could choose adequate values for the Bass model parameters to forecast new automotive technologies diffusion with a focus on Electric Vehicles. It considers parameters provided by the literature as well as ad hoc parameter estimations based on real market data for Germany. Our investigation suggests that researchers may be in trouble in electing adequate parameter values since the different eligible parameter values exhibit dramatic variations. Literature values appear discussible and widely variable while ad hoc estimates appear poorly conclusive. A serious problem is that ad-hoc estimates of the Bass p value are highly sensitive to the assumed market potential M. So for plausible values of M, p varies on a high scale. Unless more consolidation takes place in this area, or more confidence can be placed on ad hoc estimates, these findings issue a warning for the users of such approaches and on the policy recommendations that would derive from their use.

Bass diffusion models are one of the competing paradigms to forecast the diffusion of innovative products or technologies. This approach posits that diffusion patterns can be modeled through two mechanisms: Innovators adopt the new product and imitators purchase the new product when getting in contact with existing users. Crucial for the implementation of the method are the values assigned to the two parameters, usually referred to as p and q, which mathematically describe innovation and imitation mechanisms. The present paper is based on the findings of a research project about policy measures to promote the diffusion of Electric Vehicles in Germany. It investigates how practitioners could choose adequate values for the Bass model parameters to forecast new automotive technologies diffusion with a focus on Electric Vehicles. It considers parameters provided by the literature as well as ad hoc parameter estimations based on real market data for Germany. Our investigation suggests that researchers may be in trouble in electing adequate parameter values since the different eligible parameter values exhibit dramatic variations. Literature values appear discussible and widely variable while ad hoc estimates appear poorly conclusive. A serious problem is that ad-hoc estimates of the Bass p value are highly sensitive to the assumed market potential M. So for plausible values of M, p varies on a high scale. Unless more consolidation takes place in this area, or more confidence can be placed on ad hoc estimates, these findings issue a warning for the users of such approaches and on the policy recommendations that would derive from their use.

This study reviews and critically discusses correction-procedures (also called "unsmoothing-procedures") for appraisal-based indices.Indices tracking values of direct commercial real estate investments are traditionally constructed in an "appraisal-based style" : Since transactions and corresponding prices of individual properties are scarce, values from regular intervals of appraisals for each "index property" are taken for index calculation. Alas, appraisal-values neither necessarily match transaction-prices nor true market values of properties. Instead, they can deviate from market-values due to biases, which arise in appraisals and index construction processes. In the past, some scientific authors suggested to correct (or "unsmooth") appraisal-based indices from several types of biases. They claim that the corrected index returns should rather match the returns of true market values than the original index returns.Primarily, appraisal-based real estate indices were calculated and published for the USA and UK. Those countries are considered as convenient target markets for investors. Due to its early launch, nowadays one long series of an appraisal-based index, which is available and appropriate for time series analysis, is the NCREIF Property Index for U.S.-properties. The 'total' index is composed of an 'income' and a 'capital' (or 'appreciation') component. So the focus of this study is in an application of the correction procedures on the NCREIF Appreciation Index. The techniques of the correctionprocedures are discussed referring to the NPI. Also meaningful modifications are proposed for the correction procedures.

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