BACKGROUND Noncompliance to treatment assignment is an inevitable occurrence in randomized clinical trials (RCTs). Intention to treat (ITT) is generally considered the best method for addressing noncompliance in RCTs. Alternatives to ITT exist, including per protocol (PP), as treated (AT), and instrumental variables (IV). These three methods define participant compliance dichotomously, but part...

The evidence-based medicine (EBM) movement was established to combat capricious reasoning in clinical care, particularly arguments from authority. Critique of authority and appraisal of evidence remain EBM's core values and should be revisited in this era of EBM's maturity and influence. We are now faced with a new form of under-questioned authority: evidence from well-designed and methodologic...

After a non-inferiority clinical trial, a new therapy may be accepted as effective, even if its treatment effect is slightly smaller than the current standard. It is therefore possible that, after a series of trials where the new therapy is slightly worse than the preceding drugs, an ineffective or harmful therapy might be incorrectly declared efficacious; this is known as 'bio-creep'. Several ...

BACKGROUND Recruitment to clinical trials is often problematic, with many trials failing to recruit to their target sample size. As a result, patient care may be based on suboptimal evidence from underpowered trials or non-randomised studies. METHODS For many conditions patients will require treatment on several occasions, for example, to treat symptoms of an underlying chronic condition (suc...

The reproductive potential and damage functions for Meloidogyne hapla and M. arenaria race 1 on Virginia-type peanuts (Arachis hypogaea cv. Florigiant) were determined over 2 years in microplot experiments in North Carolina. Peanut yield suppression and damage to pods as a result of galling were greatest in response to M. arenaria (P = 0.01). Damage functions for the two species were adequately...

Harmony grape rootstock displays resistance to several Meloidogyne spp. but that resistance is not durable in commercial vineyard settings. A 2-year experiment in a microplot setting revealed host specificities of two virulent populations of Meloidogyne arenaria and an avirulent population of Meloidogyne incognita. In a subsequent split-root experiment, the avirulent nematode population was dem...

Field microplot experiments were conducted from 1995 to 1998 to determine the relationship between fresh shoot weight of stalk-cut broadleaf and shade-grown cigar wrapper tobacco types (Nicotiana tabacum L.) and initial density of Globodera tabacum tabacum second stage juveniles (J2) per cm(3) soil. Total shoot weight was negatively correlated with initial nematode densities of 12.3 to 747.3 J2...

Field microplot experiments were conducted from 1987 to 1992 to determine the relationship between fresh weight leaf yield of shade tobacco (Nicotiana tabacum) and initial density of Globodera tabacum tabacum (encysted J2 per cm(3) soil). Initial nematode densities of 0.1 to 1,097 J2/cm(3) soil were negatively correlated with leaf yield, total shoot weight, and normalized plant height 5 to 6 we...

Microplot and field experiments were used to examine the plant-growth stimulation frequently associated with the use of aldicarb on tobacco in the absence of major pests. Aldicarb rates of 1.5-4.5 kg a.i./ha enhanced tobacco growth and yield in most experiments, but higher rates (>/= 4.5 kg) usually resulted in a neutral to negative effect. Tobacco cultivars NC 82 and Speight G-28 were more res...