Questions tagged [baseline]
A base measurement for comparison. Usually a measurement prior to treatment, of a control condition, or of the assumed population.
36
questions
0
votes
0
answers
10
views
Best way to compare group characteristics
I have a dataset (say N=200) of which a subset (N=150) have undergone a certain assay. I want to be able to say that the subgroup N=150 is not significantly different from the entire population (N=...
- 1
0
votes
0
answers
20
views
Compare two groups with differnt treatments and different populations
I will simplify my research question. I have 40 patients (group 1) with assessed a variable v1 (e.g. their blood preassure) at timepoint 0 ( v1(t0) ). After treatment (treatment 1 at timepoint 1) I ...
- 11
1
vote
0
answers
15
views
Meta-analysis for studies with both baseline and follow-up measurements in both control and experimental groups
I am new to meta-analysis. I did a quick search, and I think I can wrap my mind around generating cohen's d and its variance when there is only a single distribution for each of the control group (C) ...
- 281
0
votes
0
answers
15
views
Resample the training data before or after train a baseline model?
I'm working on an unbalanced dataset with three classes. The original proportions are:
class 1: 48%
class 2: 37%
class 3: 15%
First I'm gonna train a baseline model and I would like to know if I ...
1
vote
0
answers
21
views
Quantitatively determining a "baseline" value for a dataset
I'm wondering if there's a clean way to quantitatively find the "baseline" of a data set, or more specifically, a threshold below which the majority of samples are clustered. For the example ...
- 11
0
votes
0
answers
41
views
Distance from mean in multivariate statistics
I have some code that calculates deviation from the mean for a series of univariate data. It calculates the mean and stddev for a window of data points, and compares the latest datapoint using $\mu$ ...
- 101
0
votes
0
answers
32
views
Precision-Recall curve in terms of conditional probability
To plot the PR-curve, we need to construct precision in terms of bayes theorem
$$
Precision = P(Y=1|Y'=1) = P(Y=1| q>q_t)
$$
where $Y$ is the true class, $Y'$ predicted class and $q_t$ is a ...
- 101
2
votes
1
answer
267
views
What exactly is a "persistent/persistence model"?
I'm new to time series forecasting and only got previous experience with image processing in therms of neural networks. My goal is to do create an ML forecasting model for time series data. Currently ...
- 33
1
vote
1
answer
590
views
Repeated measures ANCOVA interpretation – significant covariate/test day interaction
I am in the last phases of my master’s thesis, and came across a question regarding my data analysis results that I cannot seem to find a clear answer for.
For context, my data is from a randomised, ...
0
votes
1
answer
48
views
Follow-up question on comparing predictor in regressions over two groups
Using a previous Stack Overflow thread as a guide:
I have two groups and I want to see how changes in a variable are predicted by variable 'baseline'. And then I wanted to see if there are group ...
- 1
1
vote
0
answers
18
views
Is there a mathematical way to show why exactly adjustment for baseline helps in longitudinal randomized studies and NOT in non-RCTs?
How exactly adjustment for baseline helps to minimize the bias and increase effectiveness in randomized trials?
I heard about:
it minimizes the unexplained variance - but how?
it minimizes the ...
- 59
0
votes
0
answers
64
views
Adjusting for baseline when time is a covariate, what is the interpretation of $y(t=0)$?
When one aims to estimate the treatment effect over time, it is recommended to include the baseline value as a covariate. Assume continuous outcome $y$, continuous time $t$, categorical treatment $x \...
- 1,798
1
vote
0
answers
41
views
How is it possible, that statisticians have OPPOSITE view on the analysis of change from baseline adjusted for baseline?
I always thought, that mathematics, thus statistics, are both strict sciences. So, two mathematicians cannot speak about the same topic and have contrary views on it.
In the pharmaceutical industry, ...
- 61
0
votes
0
answers
156
views
Why is the baseline x time interaction included in clinical trials models (MMRM)?
I noticed, that many, many times, when the longitudinal studies are analysed for efficacy, the following components are taken as fixed effects:
time
treatment
time : treatment (interaction)
baseline ...
- 41
1
vote
0
answers
45
views
How to adjust for the baseline difference between groups for a histogram
I have data from an experiment that tested responses to stimuli in females and males. I measured baseline for both groups prior to presenting the stimuli. The baseline for males is higher than for ...
- 11
13
votes
4
answers
1k
views
How simple should a Baseline model be?
I was making baseline model and was wondering how much time I should spend on it.
I've found a lot of article about the purpose of a baseline model, for instance;
A baseline takes only 10% of the ...
- 153
0
votes
0
answers
218
views
How to measure a pre-post change?
I would be very grateful for any advice on how to analyze the data of a small study I have conducted. The study has only one group of participants and their performance in a test was measured for 5 ...
- 31
0
votes
0
answers
212
views
1
vote
1
answer
215
views
Is it a problem if my model does not perform as well as the stupid model?
Usually what I see is that the baseline accuracy and the base model have different accuracies so then the goal is to clean the data and do some feature engineering etc to build a model that performs ...
- 137
1
vote
1
answer
29
views
Baseline adjustment when both pre- and post values are subject to left-censoring
Assume $X$ is a binary treatment variable, $Y$ is a continuous variable measured pre- and post-treatment $(Y_{pre}$, $Y_{post})$, and $Z$ represents the remaining covariates. Both $Y_{pre}$ and $Y_{...
- 11
1
vote
1
answer
307
views
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 ...
- 557
2
votes
1
answer
3k
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 ...
- 2,310
3
votes
1
answer
256
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 ...
- 31
0
votes
1
answer
601
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 ...
- 51
1
vote
0
answers
95
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 + ...
0
votes
1
answer
57
views
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.
- 557
3
votes
2
answers
390
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 ...
- 423
5
votes
1
answer
672
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,...
3
votes
1
answer
368
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 ...
- 9,329
1
vote
0
answers
47
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 ...
- 21
2
votes
0
answers
72
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). ...
- 9,329
1
vote
0
answers
118
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 ...
- 9,329
12
votes
2
answers
2k
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 ...
- 9,329
1
vote
1
answer
141
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 ...
- 561
2
votes
1
answer
988
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 ...
user271077
1
vote
1
answer
2k
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 ...
- 11