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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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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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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21 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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13 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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11 views
Relative Change Model
In a toy experiment meant to generate data for a pedagogic multiple regression example, 7 types of gummi bear with different composition of ingredients (covariates: price, protein and carbohydrate per ...
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10 views
percent change from baseline
i have a 10 samples with baseline and follow up scores. I need to calculate a percentage increase or decrease based on the scoring scale, in this case its 0-56, and the objective (whether the ...
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3answers
75 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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29 views
Is it possible to do a regression with a factor as IV and change in that same factor as DV?
I would like to find the factors that predict change on a user satisfaction survey. I have chosen to use a linear regression (actually PLS regression but I am not sure if that detail is relevant here)....
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114 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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31 views
Pre- and post-intervention difference between standard deviation scores
My first research question is based on establishing whether mental toughness is a trait like construct or a skill that can be manipulated through training and experience.
I am using descriptive ...
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1answer
49 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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100 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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95 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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46 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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30 views
Repeated measures ANOVA vs ANCOVA
I’m trying to choose the appropriate statistical test for the reanalysis of a clinical trial.
In the original trial, the investigators compared five outcome measures between two groups randomized to ...
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3answers
1k 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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205 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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75 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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79 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 ...
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25 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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55 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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253 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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534 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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27 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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615 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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26 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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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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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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114 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
28 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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42 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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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
45 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 ...
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379 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 - ...
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252 views
How to tell if there is any improvement, statistically
My statistic knowledge only goes so far as to understand those basic statistic terms, instead of applying them, yet this is a questions on applying statistic knowledge into real world case.
For ...
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29 views
Will a t-test for the change in repeated lab results be much different than a mixed model?
I have a dataset of 200 patients with lab results at time a given year and the previous year. The hypothesis is that in patients with a high-risk disease (group A) the change in the lab result will be ...
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1answer
375 views
Which statistical test to use using pretest and post test data? [duplicate]
I am trying to analyze data which there were two groups, control and treatment. Both groups were given a pre-test and post-test. The control group received differentiated instruction and the control ...
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1answer
228 views
Can I combine binary and continuous data to meta-analyze prospective changes over time?
I'm interested in conducting a meta-analysis of mental health in the first year after an event. I have a set of prospective studies that assess mental health at baseline (i.e., immediately after the ...
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1answer
2k views
Effect of baseline on change over time in mixed models?
I was wondering whether and how it is possible to model, within some sample, change of outcome over time which is dependent on the baseline value of this outcome, using a mixed model?
Imagine, for ...
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177 views
Analysis of change in ordinal variable between groups
A trial I was asked to analyze has examined 3 groups - intervention1, intervention2, and placebo, and compared before and after grades - an ordinal variable on a scale of 0 to 6.
How can one tell if ...
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2answers
54 views
What's the best measure of how much a value changes?
From a car, I get a value every second for accelerator pedal, from 0 to 100%. When you don't touch it, it reports 0%, and when you kick it to the max, that is 100%.
I want to calculate how much ...
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1answer
379 views
paired t-test as a simple latent change score model
UPDATE: This problem was (embarrassingly) solved by specifying the intercept in the regression equation as shown below:
...
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1answer
33 views
Which regression to use with a dependente variable which is the sum of six ordinal scores
I need to study which variables influence the change in a score after a treatment.
The problem is that the score (from 0 to 18) is actually the sum of six 4-levels (0 to 3) ordinal variables which ...
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403 views
Using repeated measures change/trend as a predictor variable
I have repeated measures of happiness for a sample of participants, and a single measure of satisfaction for each of the ...
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1answer
257 views
Best way to examine longitudinal data?
I had 20 patients come to clinic once a month for 6 months. At each visit we collected baseline data. We then gave the patients 3 different treatments to see the effects for each visit. Thus we have ...
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1answer
957 views
change scores as predictor variables in a repeated measures multilevel model
I am using SPSS mixed to create a longitudinal multilevel model. Level 1 is observations and Level 2 is participants, so observations are nested within participants. I have multiple continuous and ...
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1answer
42 views
Distribution of data is very separated in my graph
First post here but I am quite stuck.
I plotted the date an award was given to a university, against their change in score (I calculated an index of change). It has given me this graph which i am ...
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120 views
Is it possible to use repeated measures ANOVA/ANCOVA with three change scores when one of which is an aggregate of the other two?
I have one independent variable and a dependent variable measured at three time points in a longitudinal cohort study, and plan to analyse them with a mixed between-within ANOVA. I have considered ...
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1answer
2k views
How to test for significance if groups differed at baseline?
I have a situation where I want to test for a statistically significant difference in the percentage of customers who own a product among two groups. The treated group gets a marketing message, and ...
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1answer
58 views
Test to evaluate if two delta values are associated?
I have an observational cohort. Subjects have lost weight. I wish to see if the weight they lost is correlated to an increase in break down of amino acids muscle. I have values from 2 time points ...
