Questions tagged [research-design]

Methods and tips for designing and conducting effective research.

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Defining an independent variable?

I am conducting a small study where one class is taught similar (but not the same) concepts over two separate lessons. The first lesson, the teacher will deliver the lesson to the class. The second ...
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Right type of randomization / random allocation for low base rates

so I have a question on the correct "name" for the random-allocation to one of two treatment groups or one control group. We designed two interventions (readings material): one on ...
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Difference in difference with multiple treatments

I have a setting in which there are three disjoint groups as follows; (1) a group which does not experience any change, i.e., controls, (2) a group who receives treatment 1, and (3) and a group who ...
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Ordinal Regression - Using a Continuous Attribute of 3 Categories as a Covariate as a Proxy for the Categories

I'm conducting an ordinal regression with SPSS 28. I have 3 subsets in my data (n=87 total, mostly equally distributed between the subsets) that represent 3 different scenarios where study ...
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Operationalizing my research model in R - moderation and mediation in one model

Below you find my research design which I want to operationalize in R. I began with operationalizing the mediator in R through lavaan. Now I want to know whether/how I can add the displayed moderators ...
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In a diff-in-diff or regression discontinuity research design, why is it important to describe why the counterfactual is a plausible one?

I've heard it mentioned that in difference-in-differences, regression discontinuity, or even in some other quasi-experimental research designs, that the counterfactual should be explained as a ...
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categorial (binary) dependent variable with several predictors: which study type?

I plan to conduct a logistic regression with a categorial dependent variable and several predictors. Anyway, I want to pregister my study but I could not find out how I would name this study type. ...
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DoE for optimization / control approach?

I'm wondering whether a DoE approach could somehow be used as kind of an optimization algorithm? One of my current tasks is to find a set of five parameter which max a sixth one (see here for more: ...
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Assess whether distance from competitor affects sales in stores

Suppose I'd like to investigate whether proximity of a competitor store affects sales in my stores. I'm struggling on how to frame the question from a regression perspective. Furthermore, there may be ...
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How to show how biased a statistic is in a non-random sample, knowing the parameter in the general population?

I have a convenience sample, and want to show readers how biased it is relative to the population it's taken from. It's absolutely certain that the sample is biased, and I want to give readers as many ...
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Best method for this study design

I have 7 independent variables age (continuous variable), body mass index (continuous variable), gender (catagorial variable), department (catagorial variable), hours/day on computer (catagorial ...
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Why are global search algorithms not used in DoE?

I'm reading about Design of Experiments via various textbooks (e.g. Montgomery's), and powerful global optimization methods (such as Ant Colony Optimization) are not used. They rely only on a basic ...
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How to study the overfitting of a classification model in my research paper?

I do research on a dataset having texts, I split them into 80% training and 20% for testing. I submitted my research article to a journal and the reviewers responded with major revisions that include ...
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SPSS and Research Design/Analysis HELP

For my Major Research Project, I am investigating: Online versus Virtual Learning Environments - to determine the effect of student engagement on levels of presence when comparing these two ...
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Multiple Sclerosis: study design to beta test a software

I am a beta-tester of a software that is intended to help the radiologist to interpret MRI reading of Multiple Sclerosis (MS). MS is a disease that, over time, could lead to new lesions, expanding ...
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Random sampling of consumer IDs over time that allows entry of new consumers

I have a Dataset of consumers over 20 months. Each consumer is identified with a unique ID of four digits, which can be 0-9 except for the first character, assigned upon entry. Each month, some ...
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Simple Random Sampling vs Stratified Random Sampling

I'm currently diving into sampling methods and I've read an introduction on the basics of them. However, I found myself getting confused on a particular example and my book provides no answer. Let's ...
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How is Jack & Suri's (2014) study a difference in difference model?

I have a question about a study that I want to replicate, namely the study Jack & Suri (2014): 'Risk Sharing and Transactions Costs: Evidence from Kenya’s Mobile Money Revolution' (available here: ...
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1 answer
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Do control variables in regression models have to be confounders? [duplicate]

So everything I'm reading on this throws out a different answer. Do control variables in regression models have to be confounders, that affect both the independent and dependent variables? I have an ...
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What study design I have if I tried several conditions on the same group of people?

If I have a group of 10 persons with DBS and tried several stimulation conditions on them (for example different frequencies), how can i call this sort of study design?
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3 votes
2 answers
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What is the best statistical tool to use for analyzing the relationship between multiple Ordinal IVs and a single Nominal DV?

I am conducting a quantitative correlational study. The ultimate goal of this research is to determine the relationship between the multiple independent variables and a single dependent variable. So, ...
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quantitative research designs-mixup

I am just learning 4 quantitative research designs, sometimes I am not sure which one to choose. 1-Descriptive Research Design 2-Correlational Research Design 3-Causal-Comparative Research Design 4-...
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In a 2-Factor Repeated Measures design, Why do the ANOVA Expected Mean Squares have the values that they do?

I am studying experiment design, and I am trying to understand why certain designs have the Expected Mean Squares that they do. Today, I want to ask about a particular design: the 2-Factor Repeated ...
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What ANOVA or any other test should I use if I have two independent variables and one dependent variable?

I have four groups - one group that will look at condition A, one at B, one at C and one is the neutral condition. The groups are comprised of different genders and age groups (ranging from 18-70). ...
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1 answer
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How do you sample without a sampling frame?

I want to research the returns to education in my city as well as assess whether people who have studied abroad on average earn more than those who have studied within the country. The data required ...
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1 vote
1 answer
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In clinical trials, why do we not always use Equivalence trials instead of superiority and non-inferiorty?

So I understand what these three types are aimed for, I know they answer different questions. However, why wouldn't we always use equivalence trials? I mean if for example were are comparing two drugs ...
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2 votes
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Why do discretised predictors have lower statistical power than continuous predictors?

In designing an analysis, I'd like to decide between using discretised variables versus using the original, continuous variable (the reason being that in this particular case, collecting discretised ...
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Using Pearson Moment Correlation For Establishing Validity Between Two Questionnaires

I'm moderately new to psychometrics and test design, and I'm currently in the process of attempting to develop a questionnaire that measures soft skills (communication, collaboration, work ethic, ...
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Mixed-effects model: Combined analysis of two separate within-subject data sets?

I have conducted two separate experiments, let's call them Exp. I and Exp. II. Both experiments were carried out applying a within-subject design, but different individuals were used in Experiment I ...
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How to call this experiment research design?

I am doing research in user interface design. I will conduct a user study where the participants will have to give label to a sentence(positive or negative sentiment). To label sentences, the user ...
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1 answer
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ANOVA or T-test for multiple groups, each group with a set of observations?

Can someone please advise on which sort of experiment or test I should run for the following. I want to know which messages would potentially resonate more within a population. I have conducted ...
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How does two-step randomization affect the variance partitioning in an ANOVA?

I am trying to understand how multi-step randomization affects ANOVA results. For example, I can think of a pair of experiments, both with 2 crossed factors, FxG. In the first experiment, shown on ...
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Experimental, Control and Waitlist Control analysis - treating waitlist control as 2 groups: experiment and control?

I have a 2.5 month intervention program that I would like to test. I have 30 experimental subjects, 30 control subjects and 30 waitlist control subjects. For experimental subjects, data were ...
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Sample Obtained is it Random Sample?

I feel embarrassed but I am confused with the below question. An interviewer plans to stand at an entrance to a popular shopping mall and conduct interviews. $$$$Is the below statement true? $$$$ ...
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Beginner questions about mediation analysis in psych intervention (2 intervention + 2 mediator system)

I am studying, and am fairly new to research methods and design, and hence hope to get some guidance on my analysis plan. I have 3 questions here, and attaching a structural model as reference. ...
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1 vote
1 answer
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Imputing missing data using testing data

My supervisor has instructed another person in my lab to use both training and testing data to impute missing values for use building a machine learning model. The results of the analysis haven't ...
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2 votes
3 answers
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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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2 votes
1 answer
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What is a "split-body" RCT?

I am reading the RCT Wikipedia page, in particular the classification by study design. There are described four types of RCT: (i) parallel groups (ii) crossover (iii) cluster (iv) factorial. Then ...
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5 votes
2 answers
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Latent Profile Analysis and Statistical Methods in Psychology

There has been a popular phenomenon that has several ‘hallmark’ components, and are uniquely associated with sexual abuse survivors. I would like to verify that the components can stand as a construct,...
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How many types of randomization are there? And how they each dealt with in the experiment's design or statistical analysis?

I am trying to understand randomization in experiment design, and am very confused, because there appear to be several types of randomization possible. For example, for a Categorical Factor with Non-...
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What is the correct analysis for this case? [duplicate]

My research question examines the best delivery time to give out instructions. My data consists of 3 conditions: receive instructions at the beginning receive instructions halfway through the task ...
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Handling existing groups with different instructors for analysis between two teaching modalities for the same course

I am working on a quasi-experimental research study. The study aims to see if there is a difference between student scores on clinical skills between a skills course that is taught in two different ...
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1 answer
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Prospective study and ascertainment of the exposure during the follow-up period

This question landed here after two migration requests from "Medical Sciences" and "Operations Research" I'm reading several prospective studies published in top journals where a ...
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Cluster regression

I have a dataset and divided the sample into 6 groups based on 4 binary criteria (e.g. "1" for has a Chief Digital Officer and "0" otherwise). Now I want to conduct a regression of ...
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1 answer
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Can this additional data improve the validity of Difference-in-Differences estimate

I am aiming to measure the impact of a treatment (a marketing stimulus) on product revenue. The data has resulted from a natural experiment. The set-up is tabulated below. Cells in the table indicate ...
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Do hierarchical linear models (HLM) require random samples?

Excuse me if this is a naive question, but do hierarchical linear models require data collected from random samples? I ask because most of the literature I find on this topic does a poor job of ...
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1 vote
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Statistical Responses/tests for Yes/No, Pre/Post surveys

I am completing a research paper regarding clinician adherence to a protocol. One of the questions is whether or not they use adjuctive therapy to the treatment. I have a pre and post survey, yes/no ...
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3 votes
1 answer
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Is a three-way fixed effects model equivalent to a triple difference estimator?

I have a conceptual question about the fixed effects model and the difference-in-differences (DD) estimator. Since a two-way fixed effects model is equivalent to a DD estimator, I was wondering if ...
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2 votes
1 answer
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Does 'proper' experimental design, in terms of ensuring scientific validity, require that the same skilled individual perform all of the measurements?

I'm not sure if this is on-topic here. If not, then please tell me and I'll delete it. I have a question about the proper way to design biomedical experiments that involve human-administered ...
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3 votes
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To what degree does reproducibility of research differ across disciplines?

Have there been any statistics meta studies that compare the reproducibility of results, as well as the willingness of researchers to provide reproducible data, analysis, and code, in their studies ...
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