Questions tagged [baseline]

A base measurement for comparison. Usually a measurement prior to treatment, of a control condition, or of the assumed population.

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Baseline Risk in XGBoost Model

I am doing a project to predict negative clinical outcomes after surgery using logistic regression and xgboost. Upon testing a few sample patients, I see that oftentimes the xgboost model predicts a ...
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Mixed Models, LS Mean Plot, and Baselines Controlled by Random Effects

I have two questions about LS Means and LS Means plots. I have a simple model I'm running in lme4: lmer(score ~ group + time + group*time + (1|sub), data = df) ...
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How to check baseline covariate balance after variable ratio matching?

In my case, each active subject is matched to a variable number of control subject. The way I can think of is to first average across the control subjects for the same active subject to make a 1: 1 ...
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349 views

how to calculate median follow-up time?

I have a hospital based dataset which conatins information on patient details. Right from their visit, drugs, diagnosis, lab tests, and death info etc. So, now I would like to compute their follow up ...
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78 views

Analyzing impact of baseline value on change score using lmm

I'm using a big clinical data set with a the evolution of a continuous lab value over time being the dependent variable and I am interested in the impact of the baseline of this value on this ...
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Why are baseline rates often excluded from statistical power considerations?

The following (slightly edited) except comes from Georgi Georgiev - one of the most reliable sources on AB testing on the internet. Let’s say you have 300 000 users a month visiting an e-commerce ...
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115 views

Dummy Classifier - No Skill Line on a Binary Classification Precision Recall Curve Using a Stratified Approach - How Calculated?

I am doing binary classification on a highly imbalanced data set where the positive value is about 1.6% of the dataset. I am training and running models but I want to compare against a dummy ...
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60 views

What is the baseline model in structural equation modeling analysis, what it may look like?

I am reading (also learning) a paper using structural equation modeling (SEM) as their analysis method. Their analysis was constructed by using a correlation matrix and asymptotic variances. They ...
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52 views

Time Treatment Effects Insignificant with Baseline Interaction - Linear Mixed Effects Model

I am running a linear mixed effects model in R. I am testing the effects of psychedelics on well-being. I have a time treatment effect (everyone took psychedelics in this cohort, there is no control). ...
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46 views

First Time Point in an LS Mean Plot with Baseline Control

Hoping you can help me understanding a request that my supervisor would like me to do in an LS Mean plot. My model is the following in lme4: DV ~ Group + Time + Group x Time + BaselineScore + ...
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For retrospective observational studies how to determine the baseline of control subjects

I understand that for the active treatment group you can consider the start of treatment as baseline. How about the control group? It is difficulty to do matching without resolving this problem.
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70 views

Significant difference between randomized groups at baseline?

A collegaue and I are conducting a pilot study in a school, the aim of which is to assess whether an "alternative" educational tool is more or less effective than traditional teaching ...
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146 views

Baseline controls for clinical trials in mixed models through random effects?

I'm analyzing multisite clinical trial data with mixed models. I have (a) a continuous DV, (b) a grouping variable (treatment vs control), (c) baseline scores for the DV, (d) a time variable (baseline,...
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111 views

How to handle large baseline difference in a randomized trial

I have results of a randomized trial where 200 participants were randomly allocated to 2 intervention groups and outcome evaluated 1 month later. I believe baseline differences between 2 groups are ...
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41 views

Which variable to take as reference category? [duplicate]

I'm doing a research about the relationship between investment risk tolerance and demographic factors such as age, generation, survey year, and control variables (including education levels,...) and I ...
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24 views

Why we cannot take baseline as predictor for change in this case

It is generally recommended that baseline should not be kept as predictor if change is outcome variable. Explanations for this have taken both baseline and final values as random (e.g. see here). ...
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35 views

Keeping baseline as predictor with change score as outcome in this peculiar scenario

It is generally recommended that baseline should not be kept as predictor if change score ...
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626 views

Is there a mathematical proof for change being correlated with baseline value

It is shown in answer here and at other places that difference of 2 random variables will be correlated with baseline. Hence baseline should not be a predictor for change in regression equations. It ...
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25 views

Using baseline categorical response as a predictor

I have a longitudinal data where the categorical response is collected at two-time points. I was wondering if it's possible to adjust my categorical response at baseline as a predictor and run a ...
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366 views

What are the advantages and disadvantages of including a baseline measurement variable in longitudinal data analysis?

What are the advantages and disadvantages of considering a baseline measurement variable in longitudinal data analysis? (A baseline variable could be the number of seizures each patient had per ...
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721 views

Base Error Rate

I am working for my final exam and I saw this sample question: Given this dataset, Assume we have the following gender detection problem, given the observed hair length and height (both discrete ...