Questions tagged [change-scores]

A single variable calculated from a variable measured at two different times (post - pre). Also called "gain-" or "difference-scores". Can also be used for other analysis of pre- and post- data.

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1answer
33 views

Why do regression models predicting a change score vs. predicting T2 controlling for T1 yield slightly different results?

I am running multiple regression models testing whether a change from T1 to T2 in my IV predicts a change in my DV (also from T1 to T2). I am running these analyses in R using the glm function. I ran ...
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24 views

How to moderate a change score?

I am using STATA to perform linear regression. Here is the analysis I would like to perform: I have weight measured at Time 1 and Time 2 (continuous variable). I have fatigue measured at Time 1 and ...
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12 views

Comparing the before and after scores between two groups

In this experiment I'm trying to make, one group of people watches a lecture series and one does not. Before the lecture series, both groups' levels of optimism, knowledge, and anxiety are assessed. ...
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45 views

Latent Change Score modeling in Lavaan; Strict vs Scalar Measurement Invariance models

I am new to SEM and currently struggling setting up Latent Change Score models for testing for Measurement Invariance (MI). I have a model with two latent factors (T1 en T2) with each 2 indicators (...
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1answer
30 views

Controlling for baseline in difference scores

I have a dataset of participants receiving various frequency of intervention. We want to see if those who received more intervention had greater improvement between pre-intervention and post-...
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44 views

How to analyse pre-post ordinal data?

I collected pre-post data from a randomized controlled experiment. The intervention for the experiment group is an educational game and the pre-test and post-test contains 10 multiple-choice ...
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26 views

Can controlling for baseline in a regression with change scores be appropriate? (within-subjects design)

I ran a regression model with a change score (post minus pre manipulation) predicting my dependent variable. Initially, I thought it might be also interesting to control for the baseline score (pre ...
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1answer
12 views

Is there any formal guideline that would indicate the necessity for adjustment for baseline when analysing change from baseline?

As in the topic. I saw many critical discussions along with mathematical explanation on why the baseline shouldn't (or mustn't) be employed as a covariate, when analysing the change from baseline. ...
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5 views

Mean difference with paired pre- post- data, don't care about direction of change

I think I've confused myself into a corner. I have a pre- and post- measure, and the change is sometimes +ve and sometimes -ve. I want to see if there's a difference, regardless of sign change. What ...
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2answers
38 views

Is it valid to use a difference score between sequential timepoints as an independent variable in a longitudinal regression analysis?

Is it valid to use change scores, i.e. like change in body weight taken between consecutive time points in longitudinal analysis where I'm using nlme/gee? For example, bodyweight at hour 3 minus ...
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1answer
19 views

Descriptive statistics for 2 variables grouped by gender with spss

I have 3 variables one categorical gender and the others are the IQBefore and IQAfter which ...
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0answers
68 views

ANOVA/ANCOVA - how to analyse

In a basic research design where you want to test how some intervention (let's say our IV is 'drinking' with the categories water; sprite; and rum) affects some continuous measurement (let's say ...
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15 views

What statistical treatment should I use when comparing before and after likert scale data? (pre and post survey)

I have a 15 item survey questionnaire that will be answered by 30 respondents. Each item are statements about difficulty experienced, the entire survey measures the difficulty experienced by the ...
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8 views

Relative change of two vectors from a pretreatment value

I have to vectors $\mathbf{y1_{post}}$ and $\mathbf{y2_{post}}$ (post because they were measured after a treatment). ...
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16 views

Two Factor ANOVA with different sample sizes but similar variances

I gave an educational intervention to Spanish speaking and English speaking students. I gave a pre and post test to these students. Due to certain issues I was not able to identify students with their ...
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27 views

method for difference score prediction

I am currently working on a longitudinal analysis (with only 2 time measurements, T1 and T2). In this non-randomized data, I have 2 time measurements of fasting glucose as my outcome, i.e. Y1 and Y2 ...
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55 views

How to create a score for a SWOT matrix (strengths, weaknesses, opportunities, and threats)

I'm developing a participatory social environmental diagnostic. To do this, I'm using primary (qualitative data from interviews with stakeholders) and secondary data (local socioeconomic data). From ...
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25 views

Given a dataset of students' exam scores across 5 years, how can I determine what consists of a significant change in score?

Suppose I have the data below, of student's scores changes between 2013-2016 in : ...
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0answers
34 views

What practical use cases are there for the static group comparison design?

As far as I understand, the only difference between "the static group comparison design" and "the posttest-only control group design" is that the latter has randomized controlled trial (RCT), in other ...
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27 views

Is GEE a good replacement for ANCOVA to analyze change from baseline on 8-points Likert item?

I was asked to analyze adjusted change from baseline. The variable of interest is a customer answer reported on 8-point Likert scale, but constructed from numbers 0 - 8, rather than labels ("weak", "...
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1answer
54 views

Machine Learning alternative for hashing [closed]

Is there a Machine Learning technique that can used to detect the slightest change in data? I know this can be done using a hash but I was just wondering if there is any machine learning technique out ...
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1answer
19 views

Two formulas giving slightly different output

I am struggling to find a proper explanation why the two methods that I use for finding the difference in EXCEL are giving me two slightly different numbers. The idea behind the task is that we have ...
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0answers
31 views

Pre post intervention analysis

I have a theoretical question about a fabricated before-after analysis with Intervention and Control groups based around a new testing method. In addition to the treatment groups and time (before and ...
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0answers
20 views

Change scores as independent variables in regression analysis [duplicate]

Can I use change scores as the independent variable in a regression analysis? If so, can anyone provide me with references for this (reliability and validity)? In addition, can anyone provide ...
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3answers
212 views

Best way to compare changes in proportions

I am reviewing a manuscript so I cannot be specific but the authors had a treatment that was supposed to improve access to care. They had a treated group and a control group. Access to care was ...
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251 views

Bootstrapping ANCOVA to deal with violations of assumptions

I have a smallish data set with three randomised intervention groups ($n$s between 13 and 22), with pre-post variables. I want to run an ANCOVA with the pre-data as a covariate and post as an outcome ...
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1answer
50 views

Analysis of one group of subjects (data provided)

I have one group ($n = 39$) of subjects pre- and post-tested on a continuous variable. I also have a gender variable coded $0$ and $1$. I was wondering how I can analyze this data so to detect any ...
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111 views

Questions about conducting Mixed-Design ANOVA in R

I have a dataset that includes one IV with 3 levels (group 1, group 2, and group 3) and a repeated DV (pre test score and post test score). I am using R, but I'm unsure what codes I should use to test ...
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1answer
199 views

What test to be used for comparing pre and post test results with categorical data?

In the past month(s) I had to get familiar with statistics in order to validate my results although my background is computer science/programming. I currently examine whether I can enhance user's ...
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1answer
83 views

Which test is appropriate for comparing Pre and Post intervention data for an Intervention. Within Sample

Im running a study that tests whether an intervention is effective in reducing depression levels, increasing well-being, optimism and self-esteem and increasing positive affect. My DV's are: ...
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3answers
3k views

paired T test: how to plot it?

What is the best way to represent a paired T test comparison for a sample with N=200 and 5 variables (only one of which is important)? nonpaired T test is not significant. A before-after graph is too ...
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1answer
381 views

Greater than 30% outliers in small dataset - what to do? Standard test? Test with outliers removed? Robust statistics?

I have a small-sample dataset representing observations from a longitudinal study. My principal interest is in 'change scores' across three parameters (A, B, C). This requires simple paired t-tests. ...
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0answers
96 views

Why not use baseline standard deviations to standardize effect size in meta-analysis?

in my meta-analysis I have studies with three kinds of data reports of RCTs which I want to integrate into one group with standardized effect sizes. studies reporting baseline and post-treatment ...
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0answers
180 views

Correlation analysis between two variables that each has pretest and posttest measures

Is it possible to conduct Correlation analysis between two variables that each has pretest and posttest measures? If yes, how? And if no, what kind of analysis should I be conducting? Edit: I would ...
2
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1answer
33 views

Assessing pre-post survey data with change scores?

I have about 50 pre & post-surveys for an intervention. I am limited to using excel and was told to only calculate the change scores. For example: ...
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0answers
63 views

using categorical variables in pre/post study

I have a continuous outcome variable, Y, that is a daily consumption score and want to study the impact of a policy change on a control group and 4 test groups t1, t2, t3 and t4. The policy change ...
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1answer
338 views

Examples of Change of baseline vs Final values

I'm learning how to perform a meta-analysis from the Cochrane handbook: http://handbook-5-1.cochrane.org/chapter_7/7_7_3_1_post_intervention_versus_change_from_baseline.htm Here they talk about the ...
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0answers
770 views

Change score analysis vs multiple regression

I have a pre-treatment (T1) and post-treatment (T2) DV measure, and 4 IVs. I am interested in how (and which) IVs predict change in DV from pre- to post-treatment, or predict post-treatment outcome (I'...
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1answer
215 views

Nonparametric test for comparing learning gains

I have two groups (control and experimental) with 16 subjects each. Their pre-test scores are statistically different from a normal distribution so I opted to do nonparametric tests. I need to compare ...
2
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1answer
28 views

When a high frequency can affect normal distribution

I have a sample of n=77 change over time scores (T2-T1). In a lot of cases a score of 0 (no change over time) is modal, at times 33% of the sample. I am wondering if this impacts the assumption of ...
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1answer
744 views

Calculating % change between two z-scores - correct?

just a quick question I was a little unsure about. Any thoughts much appreciated! Say I am running an 2 condition experimental trial where one of the outcomes is a z-score (e.g. cognitive test ...
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0answers
30 views

How to interpret post-pre change based on a variable number of events with panel-style data?

For a predictive model (e.g., like a regression or mixed model), what statistical methods are best used when one wants to model data where a variable number of observations occur between some initial ...
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3answers
2k views

Pre/Post Likert survey analysis

Online anonymous Likert survey was sent containing 13 items, the survey was sent before and after an intervention. I would like to analyze the % respondents who responded agree/strongly agree to the ...
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0answers
33 views

Is it fair to rescale my data here?

Sampling Scenario I went out in the field and got 50 baby individuals. By their nature (and not due to a treatment), 25 of them belong to the category A and 25 of ...
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0answers
122 views

How to measure Generalizability?

I conduct pre/post analyses looking at a health metrics (such as BMI) for a sample population. The sample might be around 75 people for a total population of about 500. One of the questions I get all ...
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1answer
33 views

Compare growth rate for different sized samples

I have 11 years of membership data for a denomination of churches and I want to find the top 20 growth rate "trend breakers". In my current method I have: calculated % change from the previous year ...
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0answers
52 views

Pre/Post Analysis - questions about covariates

I am trying to evaluate the impact of an intervention (0/1) on readmission rates pre- and post-intervention. Every individual has a pre-period rate and a post-period rate. A few important points: 1. ...
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0answers
24 views

Mixed-effects modelling of pairwise changes (indirect change)

It is straightforward to model "direct" changes using a mixed-effects model. Let's assume we have 3 correlated measures over time from a subject, y1, y2 and y3. One ...
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1answer
54 views

Regression to Assess if Change in Variables B & C is related to Change in Variable D…vs. Mediation?

I'm trying to help a colleague with a proposal to assess the impact of an intervention (let's call that "Variable A") and understand why the intervention is working. The intervention has three ...
3
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2answers
412 views

Paired t test-like solution in a two-group pretest/posttest design

I am analyzing a dataset where pre/post measurements are made (before/after a surgery) on patients who can belong to two groups, and we are interested in how group membership - let's call it G - ...