A treatment effect is the causal effect of some "treatment" or policy intervention on an outcome variable. Such effects can be estimated with data from randomized or quasi experiments, and clinical trials or with observational data and methods for causal inference.

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Statistical tests for comparing a skewed clinical sample

I recently surveyed 350 low-income families -- they were randomly split into two groups: control and treatment. One of the variables I am very interested in is the amount of savings of each family. ...
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1answer
95 views

Hypothesis testing - Wilcoxon test, bootstrapping, or something else?

A colleague has developed a treatment for to "prevent falls" in cognitively impaired, psychiatric patients. Since this would be very useful treatment in this population, we especially do not want to ...
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19 views

Standard deviation of lift

I am trying to calculate the standard deviation of lift given treatment and control groups, and the respective response values, which are binary, for each entity in the groups. Here is the problem in ...
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16 views

Measuring treatment effect on top-ranked subjects selected at point in time from longitudinal data

I am trying to measure the effect of treatment after some time on a group of subjects who were selected for treatment because they were the highest (top 1200) ranked subjects during a single period ...
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2answers
171 views

Using control variables in experiments?

Why would one want to control for any number of baseline covariates in a situation where the assignment to treatment group is random? My understanding is that randomly assigning treatment should make ...
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12 views

Inferring treatment start date for comparison group

I'm trying to work out the effect of treatment on a group using a counterfactual approach. However, I don't know how I can infer the treatment start date for the comparison group. For both groups I ...
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26 views

Family-wise error of dependent tests?

Say you have a drug of which you want to test wether it increases the number of immune cells in your blood. You divide your sample in two groups where one group receives the treatment and the other ...
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1answer
59 views

Endogenous treatment effects: exogenous covariates

I am interested in estimating an endogenous treatment effects model of the following form: \begin{eqnarray} Y_i = \alpha + \beta_x X_i + \beta_{z1} Z_{1i} + e_i \\ X_i = a + \beta_{z2} Z_{2i} + v_i ...
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46 views

Simulation setting for the average treatment effect on the treated (ATT)

I have a question about a simulation set up. Assume there are two groups (Z = 0 and Z = 1). The outcome for Z = 0 and Z = 1 are generated by the following equations: $Y_0 = \alpha_0 + ...
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89 views

Constructing the OLS standard error by hand to avoid regression

I am having trouble deriving the standard error of a simple regression estimator by hand. Stata code and output for a toy example using the cars dataset is below. The basic idea is that I have a ...
3
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1answer
70 views

How to correctly measure effect on heavy-tailed distribution

I ran an experiment on my website where I randomly assigned users to either the treatment or control group, and have two questions about how to correctly compute significance of the results. Some ...
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15 views

how can I determine the effect of pre treatment on post treatment? [duplicate]

I have two group male and female and I am looking in to pre and post value and I want to determine: 1. the gender effect on improvement (post-pre) 2. the initial value(pre) effect on post value.
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76 views

What to input into Wilcoxon rank sum test when three pre and three post measurements are compared?

I have measured 23 patients three times pre and three times post treatment. Now I would like to see if the treatment had a significant effect. I thought about using a Wilcoxon rank sum test for this ...
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33 views

Weighting FE regression with full matching

I have a dataset that has been partitioned into propensity-score-based matching groups using the optmatch package in R. We used full matching, so this allows any number of treatment observations to be ...
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1answer
77 views

Controlled before-and-after

I've got a study, a before-and-after controlled design. I have pre-intervention data and post-intervention data, the intervention is an educational intervention, given to general practitioners and ...
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2answers
211 views

R Package for Treatment Effect Analysis?

I could not find a package in R about Treatment Effect Analysis. So is there a R package about Treatment Effect Analysis? This means, estimating the average treatment effect, average treatment ...
2
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1answer
74 views

Treatment effect Analysis: What is Stratification and explanation/interpretation?

In this paper by Angrist a stratification estimator is used (page 16 formula (4)) to calculate the Average Treatment Effect on the Treated (ATOT). The formula is given by: \begin{align} ...
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1answer
300 views

Plot normal probability for effect estimates in factorial design in R

I have 2 level Design (DOE) with 4 factors (A,B,C,D). I've already calculated the estimates for each main effect and all the interaction effects. How can I construct the normal probability plot to ...
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90 views

How to test significance of pre-post difference scores on 8 measures (1 group)

I have a set of pre and post treatment scores on 8 measures. I'd like to test which of these show significant improvement after treatment. If I use within-subjects t tests it will mean carrying out 8 ...
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1answer
316 views

Significant difference from regression confidence intervals

I have a question about statistical significance in relation to confidence intervals from linear regression. I'm obviously far from a stats expert, and I've been searching for the answer to this, ...
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53 views

Heterogeneous Treatment Effects - How to test differences in the ATE?

I have the following problem: I want to conduct a simple Propensity Score Estimation where the treatment D is a binary variable (D=1 individual i participates in the labor market program, zero ...
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1answer
82 views

multiplicative treatment effects with standard errors

I simplified this a fair bit after finding a draft version of the Imbens and Rubin chapter. I am interested in estimating a constant multiplicative treatment effect from a randomized experiment. I ...
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1answer
510 views

Deriving effect sizes form pre-post treatment design in R?

This question is related to my previous post. In case of a meta-analysis of a pre-post treatment design I have data given from 5 studies that tested subjects pre- and post-treatment on a continuous ...
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2answers
94 views

What would be the most appropriate significance test for my scenario?

I have three groups of users $-$ $G1$, $G2$ and $Control$. The users in each of these three groups are different but are carefully selected and have similar properties. I treat each group with a ...
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19 views

Using non-treatment factors to rank patients for receiving a treatment

I'm facing a problem and am wondering if the biostats community may already have a method for it that I just haven't heard about in my field. I am doing some work with a test vs. control group and a ...
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101 views

Test for differences between treatment groups over time?

I have two treatments (rodent poisoning quadrats ($n=5$) and non poisoning quadrats ($n=5$)) and for each treatment I survey the number of individually identified invertebrates appearing across time ...
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162 views

How to tell if a continuous variable is associated with (treatment) change in another variable over time (one group, time 1, time 2)?

Hypothetical: I have treated a sample for depression and have (continuous) depression scores at intake (Y1) and at the end of treatment (Y2). I am wondering if motivation (X) at the start of therapy ...
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3answers
248 views

Can p values be used to show impact of treatment

Does it make sense to use the differences in p value to show a tendency or the 'importance' of the effect of a treatment. for example, I have treated a contaminated soil and I test the treatments ...
2
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1answer
571 views

Testing the significance of differences in frequencies across treatments using $\chi^2$ test

I've run a small experiment and need to test the data by comparing the frequencies of different treatments, specifically, whether they are significantly different. I think the chi-squared test is ...
2
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1answer
616 views

Standardized mean decomposition (Oaxaca-Blinder decomposition)

How does standardized mean decomposition differ from the simpler dummy variable regression? How does the average in mean outcomes or interpretation of results attributable to a particular treatment or ...
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2answers
234 views

Seasonality of treatment and Average Treatment Effect

I have panel data of sales for many stores in two comparable cities. One of the cities holds a special event once a month (the treatment) which is expected to boost sales across the board on that day. ...
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115 views

Testing endogeneity against decision probability

I am working with a model where the literature suggests there is potential endogeneity between the dependent variable and the primary independent variable of interest (a binary treatment). However, ...
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1answer
528 views

When can I suppress the intercept using treatreg?

Can I suppress the intercept if I know the treatment will be zero if the independent variables are zero. Also, can I suppress the intercept if I know the right hand side of the primary regression ...