On Necessary and Sufficient Conditions for Ordinary Least Squares Estimators to Be Best Linear Unbiased Estimators

Two often-quoted necessary and sufficient conditions for ordinary least squares estimators to be best linear unbiased estimators are described. Another necessary and sufficient condition is described, providing an additional tool for checking to see whether the covariance matrix of a given linear model is such that the ordinary least squares estimator is also the best linear unbiased estimator. The new condition is used to show that one of the two published conditions is only a sufficient condition.     

A FAMILY THERAPIST RATING SCALE*

This article reports the development of a scale for evaluating family therapist skills. The scale includes ten items within each of five skill categories. All items were found to discriminate significantly between videotaped segments of effective and ineffective family therapist skills. Also all skill categories discriminated significantly between experienced and inexperienced family therapists. The interrater reliability and internal consistency of the categories were also judged to be acceptable. Suggestions are presented for uses of the scale in therapist training research.     

Global QUALITY OF LIFE (QOL), health and ability are primarily determined by our consciousness. Research findings from Denmark 1991–2004

Objective: To explain the global quality of life (QOL) from 2000 indicators representing all aspects of life. Design and setting: Two cross sectional population studies, one prospective cohort study and one retrospective cohort study. Participants: (1) Representative sample of 2500 Danes (18–88 years), (2) 7222 members of the Copenhagen Perinatal Birth Cohort 1959–1961 (31–33 years), (3) 9.006 mothers and their 8820 children born in Copenhagen 1959–1961, (4) 746 Danes (55–66 years). Main outcome measures: Global QOL measured by SEQOL (self evaluation of QOL) containing eight global QOL measures: Well-being, life-satisfaction, happiness, fulfilment of needs, experience of temporal and spatial domains, expression of lifes potentials and objective factors. Results: 2000 associations; strongest between QOL and health, ability, the personal philosophy of life, the relationships to oneself, the partner and friends; weakest between QOL and 1000 early life factors, 1000 life events and 100 objective factors like income. Conclusions: Quality of life is associated with personal health and attitude towards life, rather than objective factors, life style, or life events. We conclude that QOL can be developed independently and thus be used as medicine.     

The negotiating style of Saudi industrial buyers: An empirical investigation

This study investigates the negotiating styles of Saudi industrial buyers. Thomas’s Topology as measured by Rahim’s instrument is used in this study. The results suggest that three are two dominant styles of negotiation in the Saudi context, namely: the competitive and collaborative styles.     

A New Approach for Testing Periodicity

This article describes testing for periodicity in the presence of FD processes. We propose two approaches for testing the periodicity based on Fisher's test. The first one is performed using the periodogram which has been divided into different parts. The second one is based on the discrete wavelet transform. Properties of the tests are illustrated by means of Monte Carlo simulations.     

Multiple nonlinear regression of the Markovian arrival process for estimating the daily global solar radiation

Abstract

Solar radiation is a global ecological phenomenon that affects life everywhere. In this study, a new statistical method, called the Quartiles-Moment's method, is proposed to estimate the scale and shape parameters of the exponentiated Gumbel maximum distribution (EGMD). The Kolomogorov–Smirnov test and the percentiles of the dataset are thus used to fit the dataset of the daily global solar radiation and the corresponding daily maximum temperature with EGMD. Thence, multiple nonlinear regression of the daily global solar radiation and the corresponding daily maximum temperature are produced and compared with the real dataset accordingly.     

Control charts for location based on different sampling schemes

Control charts are the most important statistical process control tool for monitoring variations in a process. A number of articles are available in the literature for the X? control chart based on simple random sampling, ranked set sampling, median-ranked set sampling (MRSS), extreme-ranked set sampling, double-ranked set sampling, double median-ranked set sampling and median double-ranked set sampling. In this study, we highlight some limitations of the existing ranked set charting structures. Besides, we propose different runs rules-based control charting structures under a variety of sampling strategies. We evaluate the performance of the control charting structures using power curves as a performance criterion. We observe that the proposed merger of varying runs rules schemes with different sampling strategies improve significantly the detection ability of location control charting structures. More specifically, the MRSS performs the best under both single- and double-ranked set strategies with varying runs rules schemes. We also include a real-life example to explain the proposal and highlight its significance for practical data sets.