Psychology is an academic and applied discipline that involves the scientific study of mental functions and behaviors.

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Mixed Model Analysis of Experiment Data using lmer() Function (lme4 package in R) where Levels in Stimulus Grouping Factor equal Observations

I am running a post-hoc analysis on the data collected during an experiment in which 15 unique stimuli were presented to participants. Having run a least squares regression using the lm() function in ...
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2answers
72 views

What is the right way to analyze a nested design in R?

I know that there are already a host of questions about nested designs but many of them haven't been answered or come from biological domains which I sometimes find hard to transfer to my domain. I ...
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2answers
46 views

Which test do i choose to conduct on my Likert scale data?

I have been doing plenty of research into which test I should use on my Likert scale data and i am becoming more confused as there are so many people saying different things. I am currently doing my ...
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6 views

Standardising data within-subjects when analysing distributions

Analysing behavioural data, Spivey, Grosjean and Knoblich, (2005) wanted to show that their results came from a unimodal distribution, rather than from averaging over subpopulations in a bimodal ...
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1answer
148 views

Variable A predicts B, variable B predicts C

I have pre - post data on quality of life, depression, and self-esteem. I hypothesize that changes in self-esteem from pre to post cause changes in depression, which in turn cause changes in quality ...
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1answer
74 views

Interaction insignificant, main effects significant

I am using modprobe syntax on SPSS to test an interaction between narcissism and rumination on a dependent variable, aggression. I get a significant effect of rumination (b = .6450, t = 2.32, p = ...
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23 views

What would be an ideal measure for the synchrony of laughter?

I am exploring the relationship between the quality of connection two people share and the tendency for their laughter to synchronize. In order to do this, I need some way to quantify the degree of ...
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1answer
19 views

Non-differentiation

I'm trying to assess the level of non-differentiation for a web survey I am doing. It features six pages of several Likert items on each page with a 6 point scale, followed by a seventh page of ...
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22 views

Two Groups Time 1 and Time 2 Nonparametric

I want to look a the effect of an intervention on work satisfaction and motivation. The data not normally distributed. I have two groups, intervention and control, with 11 in each group. I measure ...
2
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1answer
37 views

Psychology / heuristics of $\Pr(A)\le \Pr(B)$ when $A$ is a subset of $B$

A while ago I read about the flaws people have in assigning probabilities to events based on their beliefs and experiences. For some reason, I started thinking about that today, and realized that I ...
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12 views

Chi goodness and Fishers: some theoretical issues post-experiment

I have run a simple experiment under four conditions: the Control, Technique A, Technique B, and Technique C (which is a+b) The dependent variable is compliance (e.g. Yes/No) These are my results ...
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0answers
127 views

Within-subjects model in JAGS/stan

I have a general question regarding a varying intercept / varying slope model in jags/stan: I have data from a psychophysics experiment, with one covariate, one within-subjects factor and several ...
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2answers
93 views

Assessing group differences on multiple outcomes

I have one independent variable with two levels: Gender (Male and Female), and dependent variables will be composed of three test scores: Impulsivity, Assertiveness, and Social Desirability. My ...
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2answers
113 views

Which statistical topics to teach in European Studies study programme?

Next year, I will teach statistics in bachelor study programme European studies (Faculty of Social and Economic Sciences, Comenius University in Bratislava). According to programme description, ...
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2answers
129 views

Should I use raw scores or profile scores for variables in a regression model?

I'm trying to build a regression model to predict subjective memory reports based on the following predictors: objective memory test, illness perceptions, verbal fluency, and mood. I also want to ...
4
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1answer
66 views

What would be a better alternative to two balanced latin squares (human subject experiment)?

Instead of running a certain balanced latin square twice (if you have m experimental conditions but 2 m subjects), what would be a better approach (to cover twice as many of the possible orderings and ...
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0answers
85 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
496 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
262 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
608 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. ...
4
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1answer
158 views

How to compare the effect of age on brain volume across different brain regions when the regions are of different sizes?

I am working on analyzing volumetric information extracted from the brain. In particular we would like to compare the strength of effects across three different regions (say x, y, and z). However, the ...
4
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2answers
441 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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81 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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1answer
209 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
207 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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0answers
80 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
363 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 ...
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0answers
186 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
70 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
268 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
1k 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, ...
11
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2answers
580 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 ...
3
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1answer
831 views

What are the primary differences between Taxometric analyses (e.g., MAXCOV, MAXEIG) and Latent Class analyses?

Recent research has attempted to determine if certain psychological constructs are latently dimensional or taxonic (i.e., including taxons or classes). For example, researchers may be interested in ...
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2answers
334 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
1k 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
337 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
256 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 ...
4
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1answer
504 views

Does a psychological scale need to be revalidated after reducing the number of response options from 9 to 4?

I have used an established 33-item empathy questionnaire. I have modified the scale from a 9 point to a 4 point scale in order to force an answer and reduce ambiguity. Do I need to retest the ...
6
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3answers
3k 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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5answers
1k 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 ...
11
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3answers
4k 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 ...
4
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3answers
314 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 ...