An Adaptive Parameter-Free Optimal Number of Market Segments Estimation Algorithm Based on a New Internal Validity Index

An appropriate optimal number of market segments(ONS)estimation is essential for an enterprise to achieve successful market segmentation,but at present,there is a serious lack of attention to this issue in market segmentation.In our study,an independent adaptive ONS estimation method BWCON-NSDK-means++is proposed by integrating a newinternal validity index(IVI)Between-Within-Connectivity(BWCON)and a newstable clustering algorithmNatural-SDK-means++(NSDK-means++)in a novel way.First,to complete the evaluation dimensions of the existing IVIs,we designed a connectivity formula based on the neighbor relationship and proposed the BWCON by integrating the connectivity with other two commonly considered measures of compactness and separation.Then,considering the stability,number of parameters and clustering performance,we proposed the NSDK-means++to participate in the integrationwhere the natural neighbor was used to optimize the initial cluster centers(ICCs)determination strategy in the SDK-means++.At last,to ensure the objectivity of the estimatedONS,we designed a BWCON-based ONS estimation framework that does not require the user to set any parameters in advance and integrated the NSDK-means++into this framework forming a practical ONS estimation tool BWCON-NSDK-means++.The final experimental results showthat the proposed BWCONand NSDK-means++are significantlymore suitable than their respective existing models to participate in the integration for determining theONS,and the proposed BWCON-NSDK-means++is demonstrably superior to the BWCON-KMA,BWCONMBK,BWCON-KM++,BWCON-RKM++,BWCON-SDKM++,BWCON-Single linkage,BWCON-Complete linkage,BWCON-Average linkage and BWCON-Ward linkage in terms of the ONS estimation.Moreover,as an independentmarket segmentation tool,the BWCON-NSDK-means++also outperforms the existing models with respect to the inter-market differentiation and sub-market size.

Simulated patient methodology as a“gold standard”in community pharmacy practice:Response to criticism

The simulated patient methodology(SPM)is considered the“gold standard”as covert participatory observation.SPM is attracting increasing interest for the investigation of community pharmacy practice;however,there is criticism that SPM can only show a small picture of everyday pharmacy practice and therefore has limited external validity.On the one hand,a certain design and application of the SPM goes hand in hand with an increase in external validity.Even if,on the other hand,this occurs at the expense of internal validity due to the trade-off situation,the justified criticism of the SPM for investigating community pharmacy practice can be countered.

Methodological Considerations Which Could Improve Spinal Cord Injury Research

Advances in spinal cord injury-based research in the last 50 years have resulted in significant improvements to therapy options.However,the efficacy of such research could be further enhanced if threats to internal and external validity were addressed.To provide perspective,a sample topic was identified:the effects of acute and chronic exercise on clinical and sub-clinical markers of cardiovascular health.The intention was not a systematic review,nor a critique of exercise-based research,but rather a means to generate further discussion.Thirty-one articles were identified,and four common issues were found relating to:(1)sampling;(2)study design;(3)control group;and(4)clinical inference.These concerns were largely attributed to insufficient resources,and challenges associated with recruiting individuals with spinal cord injury.Overcoming these challenges will be difficult,but some opportunities include:(1)implementing multi-center trials;(2)sampling from subject groups appropriate to the research question;(3)including an appropriate control group;and(4)clearly defining clini-cal inference.These opportunities are not always feasible,and some easier to implement than others.However,addressing these concerns may assist in progressing spinal cord injury-based research,thereby helping to ensure steady advancement of therapy options for persons with spinal cord injury.