One of the most common errors made by physicians in all developed countries is to say that the p-value of a test is the probability that the null hypothesis considered in the test is true or false. Eighty percent of those polled in many surveys make this mistake. The p-value of a test is the probability of obtaining a result like the one obtained in the investigation if the null hypothesis is true.
View Article and Find Full Text PDFThe original idea of rejecting studies with low power and authorising them if their power is sufficiently high is reasonable and even an obligation, although in practice this reasoning is heavily constrained by the fact that the power of a study depends on several factors, rather than a single one. Furthermore, there is no threshold separating 'high' power values from 'low' power values'. However, if the result is very significant, considering how powerful it was it makes little sense after the study has been carried out.
View Article and Find Full Text PDFAssuming that a hypothesis is true because insufficient evidence has been found to reject it is a very common error when interpreting the p-value of a test in biomedical research. For example, a value of p = 0.28 obviously does not mean the null hypothesis should be ruled out, but if we understand what it means (which is not a mathematical issue, but instead a purely logical one) that it is equally obvious that it cannot be stated that it is true.
View Article and Find Full Text PDFLeading scientific journals in fields such as medicine, biology and sociology repeatedly publish articles and editorials claiming that a large percentage of doctors do not understand the basics of statistical analysis, which increases the risk of errors in interpreting data, makes them more vulnerable to misinformation and reduces the effectiveness of research. This problem extends throughout their careers and is largely due to the poor training they receive in statistics - a problem that is common in developed countries. As stated by H.
View Article and Find Full Text PDFA very common practice in medical research, during the process of data analysis, is to dichotomise numerical variables in two groups. This leads to the loss of very useful information that can undermine the effectiveness of the research. Several examples are used to show how the dichotomisation of numerical variables can lead to a loss of statistical power in studies.
View Article and Find Full Text PDFWhen researchers request funding and authorisation from financial institutions to carry out their project, one of the first questions they are asked is: what is the statistical power of the study you are proposing? If the researcher answers, for example, 90%, and the evaluator is satisfied, it is certain that he/she is not really familiar with the subject. The power of a study is not unique. It depends on certain parameters and what happens is that, in most cases, by introducing a slight variation in the values of these parameters, the power takes on an acceptable value.
View Article and Find Full Text PDFWhen we decide to conduct a study, one of the first questions that arises is what number of individuals should be included in the sample for it to be 'representative' and for the study to be 'valid'? As in other areas of life, there are many matters for which there is no 'right' amount and different quantities are valid. The same applies here. When asked the question 'How many euros did this bicycle cost?', the answer is a definite number.
View Article and Find Full Text PDFWe thank Dr. López-Moreno for the comment [..
View Article and Find Full Text PDFObjective: The purpose of this study was to determine the acute effect of an abdominal hypopressive exercise (AHE) on linea alba morphology among women who are primiparous and to compare this effect with that of other common abdominal exercise modalities.
Methods: A cross-sectional study of 46 women 3 months after first delivery was conducted. B-mode ultrasound imaging of the interrectus distance (IRD) and linea alba distortion was performed 2 cm below (I-point) and above (S-point) the umbilicus and at the mid-point between the umbilicus and xiphoid process (X-point).
Background: Evidence suggests that bioactive peptides reduce hypertension and affect certain metabolic pathways.
Methods: Fifty-four volunteers with stage 1 prehypertension and/or hypercholesterolemia and/or basal glucose >100 mg/dL were recruited and randomized to pork dry-cured ham ( = 35) or cooked ham (placebo group; = 19) for 28 days. After a wash-out period, meat products were changed for 28 additional days.
Background: Acute intermittent porphyria (AIP) is a genetic disease characterized by acute neurovisceral attacks. Long-term clinical conditions, chronic symptoms and impaired health related quality of life (HRQoL) have been reported during non-attack periods but mainly in patients with recurrent attacks. Our aim was to investigate these aspects in sporadic AIP (SA-AIP) and latent AIP (L-AIP) patients.
View Article and Find Full Text PDFBackground: Acute intermittent porphyria (AIP) is a low-penetrant genetic metabolic disease caused by a deficiency of hydroxymethylbilane synthase (HMBS) in the haem biosynthesis. Manifest AIP (MAIP) is considered when carriers develop typical acute neurovisceral attacks with elevation of porphyrin precursors, while the absence of attacks is referred to as latent AIP (LAIP). Attacks are often triggered by drugs, endocrine factors, fasting or stress.
View Article and Find Full Text PDFObjectives: To compare self-extraction with and without a cervical collar in subjects at low risk of cervical spine injuries.
Material And Methods: Simulation study analyzing biomechanical data from inertial sensors to detect misalignment of the cervical spine during self-extraction with and without a cervical collar.
Results: Misalignment was a mean (SD) 3.
Background & Aims: Broccoli sprouts represent an interesting choice of healthy food product as they are rich in glucosinolates and their cognate bioactive metabolites, isothiocyanates able to counteract the negative effects of diverse pathologies. As obesity is linked to an inflammatory component, the aim of the study was to evaluate the anti-inflammatory action of broccoli sprouts in overweight adult subjects.
Methods: An in vivo controlled study was performed in 40 healthy overweight subjects (ClinicalTrials.
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