Sorry to bother you. But could explain p value again to us. I know it's statistical summary but of what? Lower means more accuracy correct?
(in research) the statistical probability of the occurrence of a given finding by chance alone in comparison with the known distribution of possible findings, considering the kinds of data, the technique of analysis, and the number of observations. The P value may be noted as a decimal. The lower the P value, the less likely the finding would occur by chance alone.
Any researcher begins the research with null hypothesis and alternative hypothesis. Null will be for supporting the old fact and alternative will be for the new fact invented/ doubted by the researcher/ scientist. Next step is to select one of this scientifically by using the science of statistics. For that the researcher should calculate the likelihood or probability that the difference observed in the study, however big or small, could have arisen purely by chance. This probability is known as p-value and it is sufficiently small, you can conclude that you have obtained a statistically significant difference. Confidence intervals and p-values take as their starting point the results observed in a study.
cheerleader wrote:Hope that explains it in a general way. Statisticians would do a much better job, but that's not me
Prevalence of chronic cerebrospinal venous insufficiency in multiple sclerosis: a blinded sonographic evaluation
1Department of Surgical Sciences, Umberto I Hospital, Sapienza University, Rome, Italy
2Department of Public health and infectious diseases, Sapienza University, Rome, Italy
Luciana Tromba, viale Regina Elena 324, 00161 Rome, Italy. Email: email@example.com
Objectives: To verify the prevalence of chronic cerebrospinal venous insufficiency in patients affected by different clinical forms of multiple sclerosis and in healthy subjects using the Zamboni ultrasound protocol combined with M-mode ultrasound examination.
Materials and methods: We enrolled 112 patients with multiple sclerosis and 67 healthy subjects from 20 to 67 years of age. All the patients underwent Duplex and color-Doppler sonography of the neck vessels, transcranial colour duplex sonography, M-mode study of the valve system and of venous abnormalities. Subjects were positive for chronic cerebrospinal venous insufficiency when at least two of five hemodynamic criteria of the Zamboni protocol were fulfilled. Chronic cerebrospinal venous insufficiency condition was further analyzed by a multivariate analysis including age, sex, disease duration, subtypes of multiple sclerosis and expanded disability status scale score as independent variables.
Results: No healthy subjects was positive for chronic cerebrospinal venous insufficiency, while in the sample of patients affected by multiple sclerosis the diagnosis was made in 59.8% of cases (p < 0.0001). The first criterion was the most frequent in patients affected by multiple sclerosis and chronic cerebrospinal venous insufficiency (respectively 54.4% and 76.1%, p < 0.001). The second, third and fourth criteria were never present in healthy subjects but were detected in patients with multiple sclerosis. The positivity of the second criterion was associated with diagnosis of chronic cerebrospinal venous insufficiency in 100% of cases. The third criterion had a prevalence of 52.2% in the subgroup of chronic cerebrospinal venous insufficiency patients. It was positive in 36 multiple sclerosis patients and was associated with chronic cerebrospinal venous insufficiency diagnosis in all cases except one.
The multivariate analysis showed that age, disease duration, sex, subtypes of multiple sclerosis and expanded disability status scale score were not considered predictors of this haemodynamic condition.
Conclusion: Chronic cerebrospinal venous insufficiency is a haemodynamic condition strongly associated with multiple sclerosis and is not found in normal controls. The addition of M-mode ultrasound to the diagnostic protocol allows improved observation of venous valve abnormalities.
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