What is recommended statistical test to compare survival curves estimated by the Cox method when there is a mixture of several types of covariates?

30 April 2014 1 5K Report

Continuous and non-continuous covariates.

I typically use the Mantel method, however, there are also the Breslow-Gehan and Tarone-Ware methods. The Mantel is the most conservative of the 3 and thus your type 1 error rate will be the lowest but as you add covariates you will sacrifice power.

Badges
Science topic

More Carlos Martínez's questions See All

Using OBD technique i am trying to measure laser induced shockwaves velocity i found that at start velocity increases and then decay?

i am unable to interpret why its increases in start as shown in figure

11 August 2024 2,179 1 View

Tissue homogenization in mouse with FastPrep-24™ 5G - is the D matrix system useful?

I need to lyse and homogenise mouse tissues. So far I have experimented with liver and lung tissue, using matrix D. The liver was completely lysed with 6 repetitions of the standard program, but...

31 July 2024 9,186 0 View

Can I use DNA a ladder for RNA samples in agarose electrophoresis? Or It is preferable to use cDNA amplified from RT-qPCR for the same samples?

I performed a nucleic acid extraction using 2 protocols for RNA extraction (Dengue Virus) and one parameter I need to evaluate is the integrity of my RNA samples. In this case, I can't use a RNA...

09 July 2024 4,857 2 View

What does a decreasing 𝐶𝑒 vs. 𝑄e plot indicate in an adsorption isotherm?

I am conducting adsorption experiments in a liquid medium, and one of my samples showed a decrease in Qe values with an increase in Ce. Has anyone encountered this behavior before? What does it...

26 June 2024 7,304 2 View

Expert in advanced statistics interested in contributing to an academic article on the adoption of digital innovations in agriculture?

We are looking for a highly qualified researcher with expertise in advanced statistical analysis to contribute to a scientific article to be submitted to a prestigious journal by the end of the...

13 June 2024 569 4 View

Word error in a title / full text (1 page) shared: may I correct it ?

A recently published visual abstract should have the title "Word First Myelography..." instead of the error "Mielography". (the 2 other text references in the article are correct) I am changing it...

20 May 2024 8,134 1 View

Fluorescence spectroscopy: signal from water?

In order to proceed with the quantification of an Azide Alkyne Cycloaddition reaction efficiency by using a fluorogenic probe with Cy5-DBCO, I first need to construct a calibration curve. The...

16 May 2024 6,266 5 View

Would the concentration of CFSE+ particles in EV samples be a more accurate way of measuring EV concentration?

Today, the most commonly used techniques for assessing the concentration of EV samples are NTA and the determination of total protein concentration. However, the concentration obtained by NTA...

16 May 2024 6,910 1 View

Is there a commercially available cell line from human cancer-associated fibroblasts (CAFs) isolated from malignant pleural mesothelioma or lung ca ?

Dear community, I am currently working on a proposal focusing on cancer-associated fibroblasts (CAFs) from malignant pleural mesothelioma (MPM). In my search among commercial cell line providers,...

05 May 2024 5,572 4 View

For DOM (dissolved organic matter) and in addition to the Follin method strategy, is there another way to determine phenolic content in the sample?

This is working with DOM (dissolved organic matter) and in addition to the acid-base titration strategy, Follin's method, there is another strategy to determine the amount of phenolic?

23 April 2024 2,197 1 View

How to learn more about SPSS and its Application?

I would like to learn more about SPSS and Its application especially in regards to data analysis. Please suggest me how I can learn more about it. Thank you so much.

11 August 2024 9,101 4 View

Can I base on reverse DNA sequences to perform alignment, convert to amino acids and GenBank submission?

I have reverse sequences (AB1 format), can I base on reverse DNA sequences to perform nucleotide alignment, convert nucleotides to amino acids and deposit the sequence in GenBank database?

11 August 2024 5,138 1 View

Baseline drift in HPLC? What causes this?

Hello, Why do i see this baseline drift when i compare my blank (black) to the sample (blue)? Any suggestions as to why this happened? Thank you!

11 August 2024 3,770 4 View

Text-Communication from the M1 Hand Area using BCI—and then there is Elon Musk?

Willett, Shenoy et al. (2021) have developed a brain computer interface (BCI) that used neural signal collected from the hand area of the motor cortex (area M1) of a paralyzed patient. The...

10 August 2024 7,180 0 View

Has anyone applied Python in the field of textile engineering for data analysis, automation, or smart textiles?

I'm currently exploring the application of Python in textile engineering, specifically in areas like data analysis, process automation, and the development of smart textiles. I'm interested in...

10 August 2024 7,429 2 View

How can I use the cif data obtained from rietveld refinement extracted via gsas2, for microstructural analysis using ETEX software?

09 August 2024 7,718 0 View

How are iso-frequency contours plotted?

Let's say we have a standard, regular hexagonal honeycomb with a 3-arm primitive unit cell (something like the figure attached; the figure is only representative and not drawn to scale). The...

07 August 2024 1,937 1 View

How to prepare the nanoparticle treated fungal sample for Environmental SEM analysis?

A fungal strain was treated with nanoparticles. We want to do an environmental SEM analysis. So could anyone share your views on preparing the sample? Thank you.

07 August 2024 5,307 1 View

How to normalize and take the significance of the MTT OD values with 3 replicates for the same cell-line?

Hi, I have a question about normalizing the MTT OD values for doing the statistical analysis. So, if we have 3 different plates and we call them 3 different replicates, so, first we would...

07 August 2024 8,106 4 View

Why does my protein refolded to beta sheet during thermal denaturation analysis?

Hi! So i attempted to understand a novel protein behavior towards heat application by analyzing its secondary structure change. I subjected the protein to a thermal denaturation analysis using...

06 August 2024 1,989 3 View