However, when applied to data from non-randomized experiments or observational studies, model-based analysis lacks the warrant of randomization.

However, the observational evidence began to support the idea that the universe evolved from a hot dense state.

However, since the establishment of the State of Israel, and especially since the Six Day War, the Karaite Jews that have made aliyah can now again use the observational calendar.

However, childhood smallpox left him with weak vision and crippled hands, limiting his ability in the observational aspects of astronomy.

However, Babylonian techniques of observational measurements were in a rudimentary stage of evolution and it was probably beyond their capacity to define in a precise way the boundary lines between the zodiacal signs in the sky.

However, although Schwarzschild's best known work lies in the area of general relativity, his research interests were extremely broad, including work in celestial mechanics, observational stellar photometry, quantum mechanics, instrumental astronomy, stellar structure, stellar statistics, Halley's comet, and spectroscopy.

In particular, there was still no observational evidence of the westward-traveling " Kelvin " waves ; Lindzen postulated their existence theoretically .< ref > Actually, the evidence was coming in at the time, see However, Lindzen says in his 1987 recollections that he did not see this study until after the Lindzen and Holton ( 1968 ) paper was already submitted ( 1987, p. 330 ).</ ref >

However, there is still no corroborating observational evidence for the existence of these iron particles.

However, the NHS Knowledge Service pointed out that this study, like most human diet studies, relied on observational data. The NHS concluded that the lack of a control group, and the small sample of size of the study, compromises their conclusions.

However, it should be noted that these are some of the most common targets when viewing the moon, and this correlation could be an observational bias.

However, medical education started to be restricted to the confines of the hospital as a consequence of the development of the clinical gaze and the confinement of patients in observational infirmaries.

However, ongoing continuation is predicated on the assumption that the observational analysis is not an ' ill-posed ' one.

However, he meticulously recorded observational detail on practical research, and subsequently advocated not only this practice, but its publication, both for successful and unsuccessful experiments, so as to validate individual claims by replication.

However, those who have had LASIK must enroll in an observational study, if a slot is available, to undergo training in Special Forces qualification.

However, an earlier nonrandomized, observational study reported " limited, prognostic value " of procalcitonin measurement.

However, in many applications, especially with small effects or questions of causality based on observational data, regression methods give misleading results.

However, his claim was never confirmed and it is likely that it was an observational artifact.

" However, Aristotle knew that the Earth is spherical and even provided observational proof of this fact.

However, one observational study has recently suggested that vasectomy could be a risk factor for PPA in men.

However, the Greek tradition is referring to the existence of vapours and chewing of laurel-leaves, which seem to be confirmed by recent studies.

However, studies of processes that

However, Paris ignored the powerful developments in quantitative studies underway in the U. S. and Britain, which reshaped economic, political and demographic research in those countries, while France fell behind.

However not all reception of Steinsaltz ' studies have been wholly positive.

However, studies have shown that blind cave fish embryos begin to grow eyes during development but then something actively stops this process and flesh grows over the partially grown eyes.

However, Dr. Andrew Newberg said that Hira stayed at the University of Pennsylvania only for brain scans on studies of meditation, not his ability to fast indefinitely.

However, the first modern studies of magnetism only started with the development of electrodynamics by Faraday, Maxwell and others in the nineteenth century, which included the classification of materials as ferromagnetic, paramagnetic and diamagnetic based on their response to magnetization.

However, in 1936, the geologists John D. Boon and Claude C. Albritton Jr. revisited Bucher's studies and concluded that the craters that he studied were probably formed by impacts.

However, it is important to note that the patients in these studies received some form of spiritual healing ( i. e. not Christian Science ' treatment ') in addition to, not instead of, conventional medical care.

However, several studies have demonstrated interference competition between coyotes and bobcats, and in all cases coyotes dominated the interaction.

However, studies of mitochondrial DNA show that the divergence between each of the three chipmunk groups is comparable to the genetic dissimilarity between Marmota and Spermophilus.

However, this meta-analysis included two large studies of smokers, so it is not clear that the results apply to the general population.

However, during 2006-8, several reviews of case reports and pilot studies have failed to confirm this effect, collectively indicating no statistically significant interaction between daily consumption of 250 mL cranberry juice and warfarin in the general population.

However the increasing use of cropmarks to identify sites in lowland areas has tended to diminish the relative value of these cairns in Neolithic studies.

However, more recent studies which use the records of civil magistrates suggest that China did in fact have a very well developed system of civil law, in which provisions of the criminal code were interpreted to allow civil causes of action.

However, according to recent studies, California chaparral is extraordinarily resilient to very long periods without fire and continues to maintain productive growth throughout pre-fire conditions.

However, molecular pharmacology studies have shown that alcohol has only a few primary targets.

Because reported AIDS cases in Africa and other parts of the developing world include a larger proportion of people who do not belong to Duesberg's preferred risk groups of drug addicts and male homosexuals, Duesberg writes on his website that " There are no risk groups in Africa, like drug addicts and homosexuals ," However, many studies have addressed the issue of risk groups in Africa and concluded that the risk of AIDS is not equally distributed.

However, Fahrenheit's interest in natural science led him to begin studies and experimentation in that field.

However, studies have shown that the removal of tuition fees at third level has increased the number of students overall and those from lower socio-economic backgrounds.

However, the individual studies still require careful critical appraisal.

However, these studies failed to account for the impact of ethnic and cultural diversity and third-world immigration in its impact on purported social well-being and income distribution.

However, new studies focus on adenoviruses that can be permitted to reproduce, and destroy cancerous cells in the process, since the adenoviruses ' ability to infect normal cells is substantially impaired, potentially resulting in a far more effective treatment.

However evidence for archaic admixture in modern humans had been suggested by some studies.