Jose Maria Bellon

Survival Analysis II

| Created: April 25th, 2010 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , Epidemiology , Evolution , clinical research , predictive markers , statistical significance , Survival -

Introduction

Survival analysis is still in constant development is one of the most important tools in clinical research. Its use is widespread because of the availability of programs on computers and statistical packages that include many of the statistical techniques of survival. However, the variety and the different possibilities of [...]

Survival analysis I

| Created: March 1st, 2010 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , Epidemiology , Evolution , clinical research , predictive markers , statistical significance , Survival -

Introduction

Survival analysis incorporates a set of statistical techniques appropriate for those follow-up studies where the response time to observe a phenomenon or event is essential. In this case the variable of interest is the time to onset of the phenomenon or event of interest, which may or may not appear in [...]

ANOVA test: comparison of the means of three or more groups

| Created: 3rd January, 2010 | Jose Maria Bellon | Category: Statistics | Tags: ANOVA , Biostatistics , multiple comparisons , Epidemiology , Statistical Error , Clinical Research , Medicine , Statistical Significance , Variance -

Introduction

In the previous chapter we saw the use of Student t and Mann-Whitney to compare means of two groups. However, if we make the comparison between three or more groups should not use these tests as multiple comparisons by pairs increased our "Type I error," he [...]

Hypothesis tests for quantitative variables

| Created: 7th September, 2009 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , Hypothesis contrast , Epidemiology , Clinical Research , T-Student -

Introduction

One of the most common situations that a researcher must confront is the comparison of the means of two groups. For example in the comparison of two treatments, in which its effectiveness is measured based on results obtained and measured numerically. In this case, you have two variables, a numerical and [...]

Hypothesis tests for qualitative variables

| Created: 1st July, 2009 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , contrast of hypotheses , correlation , epidemiology , clinical research , statistical significance , Table 2x2 -

Posted in Neumonews (2008)

Introduction

On numerous occasions, we need to analyze the relationship of dependence or independence between two qualitative variables or categorical. These variables are also called factors, while the various categories of the variable is often referred to as levels. There are different tests to measure the dependence between two qualitative variables, [...]

Correlation and simple linear regression

| Created: 1st June, 2009 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , Correlation , Clinical Research , Regression -

Posted in Neumonews (2008)

Introduction

By working with two quantitative variables we can study the relationship between them by the correlation and regression. Although estimates of both techniques may be similar in some respects and even give similar results should not be confused. The only correlation we measure the direction and strength of the [...]

Number needed to treat (NNT)

| Created: 17th February, 2009 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , Clinical Research , NNT -

Posted in Neumonews (2007)

Introduction

In the previous chapter we saw how the p was a measure of chance, which tells us the probability that chance could explain the differences observed in our study. Shows statistical significance for both an association or difference between variables that hardly can be explained by chance, without [...]

Statistical significance and clinical significance

| Created: 15th December, 2008 | Jose Maria Bellon | Category: Statistics | Tags: Biostatistics , Biomedicine , Error statistics , clinical research , statistical significance -

Posted in Neumonews (2007)

Introduction

The increasing need for researchers to generate questions to answer increasingly complex. Today the use of statistical and epidemiological terms invades the literature. The importance of statistics is such that many of the works and the conclusions from research, it should support it.

At the [...]