The psychology tag has no wiki summary.
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37 views
How to avoid regression to the mean in a simple comparison
This is a pretty simple question but I haven't been able to find a clear answer to it. I have some data from a behavioral experiment taken under two conditions (A and B); within each condition, each ...
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2answers
122 views
Is a pre-post intervention study with a control group without random assignment quasi-experimental?
I am currently rather confused about the design type for my study.
I am looking at a number of measures pre and post intervention with control group in a community sample. The sample collected was ...
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1answer
67 views
EFA clearly supports one-factor, measure is internally consistent, but CFA has poor fit?
I am exploring the psychometric properties of a 10-item self-report measure. I have about 400 cases in two independent samples. The items are completed on 4-point Likert scales. An EFA clearly ...
3
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1answer
269 views
Box's test for equal covariances or Mauchly's test of sphericity?
I am writing a report on a 2 x 3 mixed study. There is ONE within IV with TWO levels and there is ONE between subjects IV THREE levels. There are two DVs.
Sample sizes for each group is 25, 25, 27.
...
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2answers
257 views
Testing the race model inequality in R
Lets say we have hypothetical participant that is presented with 3 stimuli conditions: a flashing dot ($C_x$), a sound blip ($C_y$) and combination of both ($C_z$). We ask this participant to respond ...
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51 views
continous moderator in a within subject design
I'm a first year PhD student and I am a bit at a loss regarding which test to use, and how to calculate power for a grant proposal. Any help will be much appreciated!
I'm running all my participants ...
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96 views
What level to use when comparing subjects in a hierarchical Bayesian analysis?
Say that I have an experiment where I test the reaction time of a number of subjects where each subject makes many reaction time trials. In a Bayesian framework the reaction times ($y$) could be ...
2
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2answers
92 views
When subject-based analysis is better than answer-based (and vice versa)?
In experimental psychology one of the generally accepted practices in data analysis is the aggregation on subject level. For example, several measurements of reaction time is gathered for each subject ...
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64 views
Is ANCOVA proper for my experiment?
I've got a serious problem when trying to analyse the data of my psychological experiment. Here are the details of the experiment:
In each trial, subjects were presented with lateralized colored ...
2
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1answer
239 views
How to quantitatively analyse a semi-structured interview?
I am looking to design a study that involves interviewing children by asking them questions that relate to their values, practices, and identities. Children will be migrants who could identify to ...
4
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0answers
96 views
How to quantify moderation effect in an intervention study with multiple time points?
I want to measure a moderation effect between 3 continuous variable in an intervention study. I am using scores from self-report measures of masculinity, emotionality, and psychological distress. The ...
4
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1answer
59 views
Books on designing clinical trials for psychotherapy research
I'm designing a clinical trial that will evaluate a behavioral therapy against a control condition, and I'm looking for some good texts on this topic. There are a lot of books on clinical trials in ...
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2answers
153 views
How to calculate minF' with corrected degrees of freedom?
If you're working with crossed random effects (a sample of words and a sample of people), you should report a minF' rather than just your F1 and F2 values according to Clark (1973), Raaijmakers et al. ...
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1answer
839 views
Is it plausible to get a Cronbach's alpha of .85 with only two Likert-type items?
I was reading an article that reported a Cronbach's alpha of .85 for a two-item scale. The scale was measuring self-perceived competence. Each item was on a 7-point Likert-type scale.
Intuitively, ...
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2answers
310 views
How to deal with ceiling effect due to measurement tool?
I have collected psychophysiological data measuring the subjects' (two groups) ability to perceive vibration. A vibrating probe moves against the skin at smaller and smaller displacements, and the ...
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1answer
210 views
Interpreting effect size
One of the most widely used interpretation of effect size is Cohen's $d$, as follows:
$<.10$: trivial
$[.10,.30]$: small to medium
$[.30,.50]$: medium to large
$>.50$: large to very large
...
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3answers
738 views
Is it appropriate to identify and remove outliers because they cause problems?
This all pertains to my Psychology honours thesis.
I have two groups (Autism and control) and all participants completed four tasks. It is very important to my study that the groups do not differ on ...
4
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2answers
253 views
Calculating 90% confidence intervals in regression to identify outlying data
I have been searching for the answer for a problem with confidence intervals for a long time now, so I hope someone can help!
The two psychological papers below performed the same analysis, ...
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4answers
227 views
Internet statistics resources suitable for psychology students doing research
I am working on a new webpage for my part-time job as a methodological/statistical consultant for (psychology) students at my university. On this website I would like to place several links to online ...
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3answers
2k views
Differences between tetrachoric and Pearson correlation
Currently I'm analysing around 300 items in the field of education.
I'm interested in the dimensionality of the dataset. So I compute a matrix of tetrachoric correlation. The goal is to do a factor ...
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4answers
977 views
Is it appropriate to treat n-point Likert scale data as n trials from a binomial process?
I've never liked how people typically analyze data from Likert scales as if error were continuous & Gaussian when there are reasonable expectations that these assumptions are violated at least at ...
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2answers
2k views
Factor analysis of questionnaires composed of Likert items
I used to analyse items from a psychometric point of view. But now I am trying to analyse other types of questions on motivation and other topics. These questions are all on Likert scales. My initial ...
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3answers
255 views
Quantitative methods and statistics conferences in psychology?
What are the most significant annual conferences focusing on quantitative methods in psychology?
This could include but is not limited to psychometrics, mathematical psychology, and statistical ...
