Questions tagged [control-group]
In a comparative experiment a control group is one which does not receive the active treatment
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Repeated measures - sort of?
I do mostly econometrics but am faced with a repeated measures type sample. I can solve it as a regression with dummies, but feel like I'm losing information in the repeated cases. I know the medical ...
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Anova with a specific reference group? Dunnett's test overall p-value?
I have been trying to work through this idea for a few days now, and I think I am just really confusing myself at this point so thought I could hopefully get some help.
The basic idea is, I have 1 ...
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Appropriate statistical test to determine if uplift between control group and multiple test groups is significant (pretest/posttest evaluation)
I'm trying to evaluate whether the difference in uplift seen in below table between the test groups and the control group is statistically significant. I'm unsure about the appropriate statistical ...
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DiD control treatment group choice
I need to evaluate the impact of the Labour-Intensive Public Works programme on social cohesion using DiD. I chose a set of control variables and an outcome variable. The thing is to choose the right ...
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How to analyze a 4x2 design with an additional control condition?
I have a somewhat unusual study setup, for which I'm not sure how to analyze it properly. Basically, I have a 4x2 factorial design which assigns users to a condition A (4 levels) and at the same time ...
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Equation for Interrupted Times Series Analysis with Multiple Intervention with Control Series
I have used STATA to conduct an ITSA but am having trouble writing the equation for it.
Period A: 2005-2010
Intervention 1
Period B: 2011-2015
Intervention 2
Period C: 2016-2020
I understand the ...
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Difference-in-Difference model with multiple treatment groups
I am currently investigating the effect of the implementation of eco-labels on unit sales with a difference-in-difference estimation. I have a variable period indicating the pre- and post-period, a ...
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Can I use MANCOVA and SEM?
My project model includes one input variable, two mediators (both measured at the individual level, but one is about the team so rWG will be calculated), one moderator, and two outcome variables (...
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Choosing a method to estimate the effect of covid border closures on border regions
I am interested in identifying the labor market impact of COVID-19 border closures in border regions in Europe. I wanted to use the Synthetic Control method to compare monthly employment development ...
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I want to determine the impact of a policy on carbon emissions in a single country by doing difference in difference but don't have a control group
The policy was implemented all over the country and applies to everyone. Can I do difference in difference looking at yearly total emissions data of the country before the policy was implemented vs ...
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How to control for mortality in an assay with multiple tests and inconsistent control mortality results?
Some context : I work on insects and most of our tests are mortality assays : we subject groups of insects, in replicates (usually 5-6), to insecticides and record the mortality 24h later. Since we ...
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Three treatment groups vs one control group - only interested in comparing each treatment group separately to control - best test/follow-up test? [duplicate]
I have an analysis in which I have three treatment groups each assigned to a (different) experimental condition, and one group assigned to a control condition. I am interested in whether any/each of ...
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How to compare control group to treatment groups and also compare treatment groups to each other? Binary Data only
In my survey participants randomly got assigned to one of the four groups and had to choose between two options for three fictional purchases.
The treatment groups contain the same intervention but ...
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Compare relative increases non-paired means
I have samples from 2 timepoints: before and after treatment with X.
After treatment we want to see, if the response of one variable (one type of enzyme) to the treatment is different from another ...
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Medical experimental design with non-comparable control
My population consists of people at high risk of cardiovascular disease who are identified through standard blood tests. These people, when identified, are prescribed some standard medication.
I will ...
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How to analyze RCT with different number of measures with mixed models
I have data from a RCT analyzing the effect of an intervention on students. The experimental group had 3 measurements: before the intervention, directly after the intervention and six months after the ...
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Justifying a smaller control group in survey study
I am planning a set of studies that are interlinked. The first study collects information from 400 participants (exposure group), then some psychometrics are performed to assess the questions. In a ...
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Meta-analysis: Combining pre-treatment and control groups in different study designs
I'm working on a meta-analysis on a subject with scant literature. I'm analyzing changes in thyroid hormones in spaceflight, looking to see if there is a significant difference between pre- and in-...
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When you have a control condition, does it has to exactly the same way as the experimental condition?
So I am carrying out a research project for which I have multiple DV and covariates; A lengthy battery of questionnaires will measure these.
I am wondering if, in the control conditions, I also need ...
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What is the best analysis method to use in a prospective study using wearable data (fitness trackers) to measure health parameters?
I have a prospective study where I need to compare the effect of heat (using an index) on health parameters (heart rate, sleep and steps) of a target population (for example adults with heart disease) ...
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Control group much much larger than test group
I'm a complete noobie in statistics and this is just me being curious about a study I read online. In the study they had 150 people who had tested positive for disease X, and a control group of 4000 ...
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Comparing intervention/control group
I am planning to conduct a study which is based on an RCT design.
I am intending to conduct an intervention. During this intervention, participants and control group enter some medical data on daily ...
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How does one define what measure to use for a Regression Discontinuity design?
For example I am looking at the effectiveness of a reading learning program for 3rd graders.
How do I define an acceptable cutoff measure? Do I look at accepted reading assessment tests, such as ...
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Limits to how many control and treatment subjects may be paired in propensity score matching?
I'm working on a difference-in-differences project where we're matching up to 5 control subjects to each treatment subject using a combination of techniques to estimate treatment effects (ATT): exact, ...
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Difference-in-differences if the control group is treated later
Would a difference-in-differences analysis still tell me something important if the control group was treated later in time? Or, would I be better off only restricting my analysis to the time frame up ...
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P-value of chi-square test of independence
I need help understanding chi2 independence test scipy.stats.chi2_contingency.
Let's assume I have two samples (of different sizes) of a categorical variable with 3 possible outcomes (1, 2, 3):
Counts ...
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Matching fixed control group to multiple time-varying treatment events so that each control is only used once/uniquely assigned
you have helped me tremendously over the past years and so far, I could find an answer to any the question I had! Thanks to anyone active in this community, I don't know what I would have done without ...
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Distinction between Treatment and Control Group
I am struggling to understand how to interpret the treatment and control group in the following case of DID regression. We need to estimate the causal effect of brick kilns on downwind PM2.5 monitor ...
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Identifying groups with better response to treatment
We have tested a population (splitted in test 50% and control 50%) with a treatment. Overall, the treatment was effective - our test variable was significantly different in the treatment and control ...
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Should I include the control group on a correlation matrix?
I have a dataset of variables from a control group (healthy subjects) and patients with a disease.
Some variables are greatly increased in the disease group in relation to the controls, however within ...
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What is the best way to compare changes between two groups?
Given we have two equal-sized groups, each with a continuous pre and post-measure. E.g., in an RCT with a treatment and a placebo group and a pre and post-intervention outcome measure, and no drop-out....
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Best way to compare two treatment groups to a control
I'm trying to compare two different fertilizer treatments to a control group (no fertilizer). I ran a model like this:
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Binomial Proportion Test on test and control populations [duplicate]
I am new to statistical tests and request your help with the following question:
A company wants to test the hypothesis that it's new ad will increase it's total number of subscribers (conversion rate)...
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Determining sample size for comparing rate of occurrence between two groups
Scenario: You are running a comparative clinical study. A test product is being used by one portion of the population (Group T) and a control product is being used by another (Group C).
The Question: ...
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In a RCT, what are the risk of selection bias if no allocation bias is present?
In the Wikipedia page about Randomized Controlled Trials (RCT), the procedures section states that RCT minimize selection bias and allocation bias.
My understanding is that selection bias "occur ...
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Treatment group size vs. Control group size for difference-in-difference estimation
I am reading an unpublished paper that employs diff-in-diff to firm data containing a total of 2598 observations. Of these observations, 2474 are in the treatment group and 124 in the control group.
I ...
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MCMC fitting of Dirichlet Process or Polya Tree prior to residuals in (simple linear regression)/(2-independent-samples) problem
Consider a simple location-shift semi-parametric model with two mutually-independent samples (in what follows, $F$ is a cumulative distribution function (CDF) on $\mathbb{ R }$, the $C_i$ and $T_j$ ...
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Using opted-out customer list as a control group for targeted promotions
I have a targeted email promotion list and I want to create a control group. My friend wants me to use the "do not contact/opted out" list as a control group, but I would think that those ...
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How can someone improve a synthetic control?
This is a broad question, I know, but I feel like it's ok to ask because I searched everywhere and I couldn't find the answer.
So I was studying about synthetic control (here: https://matheusfacure....
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How to plot the graph or perform a formal test of parallel trends for generalized DiD?
A. Background:
Dasgupta, 2019, p. 2596-2597 create a baseline as below to study the impact of staggered design difference-in-differences (DiD):
The baseline identification:
$Y_{it}$ = $\alpha$ + $\...
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What is the RCT design where all participants get placebo first, then non-responders get randomized to treatment?
I'm trying to find a paper documenting an RCT design where all participants start by receiving the placebo only, and then participants who do not respond to the placebo get randomized to treatment/...
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How to calculate effect size for a pretest-posttest-control design study?
I am trying to calculate the effect size of exercise on depression. So I have 2 groups (control and intervention) in an RCT setting. I have both mean values and standard deviation of groups at T0 (...
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Does a large control group lead to violation of assumption made to use difference-in-difference methods
Does a large control group lead to violation of assumption made to use difference-in-difference method? The control group is around 10 times larger than the treatment group.
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Should I plan my AB testing accordingly to a minimum number of days or to the number of datapoints?
Here's the thing, I was planning to test a new strategy on my website. A typical AB test for a new homepage. One strategy is the current, the control; the other is the variant, the new strategy. I ...
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Control group participants
I have read a lot especially on RCT design but this hasnt been explicitly answered anywhere. Does the control group participants have to have 'opted-in' to the intervention and failed/not been ...
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Regression Model to obtain ATET
I'm working on a problem where I have two groups that both received a different treatment and one controlgroup. The total number of people in this experiment is 10,000 and the participants where ...
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Minimum sample size and power test
Suppose I have access to data on the energy consumption of a city with a population of 30000 persons. Imagine I want to test a new technology of smart energy, i.e if the energy consumption decreases ...
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Hypothesis Testing the difference in two means - Is N just the number in each group or should it also include each observation in each group?
I am working on a problem where I will be using a hypothesis test to find the difference in two means; a control group, and a test group. Each group consists of several stores where observations are ...
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How to compare score differences across time using unpaired data?
An anonymous school climate survey was administered to students in 10 schools in 2017. We have student-level data from that survey, which includes each student's overall satisfaction score (scale of 0 ...
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Control group within the country for national policy
I have a question about control group selection.
I want to evaluate a private education suppression policy.
The policy is that 70% of questions of a "national" university entrance test is ...
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