Questions tagged [statistics]

For questions about statistical methods that might be appropriate for certain paradigms within psychology, psychiatry, neuroscience, or cognitive science.

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Why does IQ have a truncated normal distribution?

I know that the IQ statistic is designed to give it a mean of 100 and that you'll certainly never find someone with an IQ below 1 or above 300, but that tells us very little about the variance or ...
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Independent t-test with d-prime [duplicate]

I am posting again as the original question was on a guest account so I cannot edit it, improve it or comment on it because I do not have high enough reputation, 50 I think? Rather than deleting this ...
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What is the field that deals with observing an individual's fitness within a system called?

Foreword: Perhaps this question is better suited for statistics.stackexchange.com, but I'm deeply interested in studying about both the living thing and the statistics side of things. Everything in ...
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27 views

How to assess the effect of individual difference measure on quadratic fit of a within-subject factor?

In my task, there are 8 levels of a within-subjects/repeated measure factor. The overall relationship that this factor has with the DV is in the shape of an inverted-U, such that their DV scores at ...
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What is the name of the survey question style that forces a choice between non-opposite pairs of items, and why is it used?

I've seen personality tests and industrial / organizational psychology tests that force one to choose between non-opposing concepts. What is the name of this question style, and what are the reasons ...
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Does putting something on a scale of left-to-right bias people in one direction?

I'd like to know what research has found about whether talking about politics on a scale of left to right biases people in any way. Perhaps to answer questions such as if the scale were to be inverted,...
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What to consider when subsampling

I have a dataset of 364 people in a control group population and about 450 in one comparison group sample and 150 in another comparison group population. We're doing a full analysis of these data. We'...
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What type of statistics test would I run for 2 different treatments assessed using 5 measurements at 4 different time points?

I have a study in which there are 2 groups: control vs drug. All individuals were assessed at 4 different developmental time points and I ran 5 tests at each time point. My goal is to see how the drug ...
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1answer
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Correlation used as explanatory device in ''The neuroscience of Intelligence'

I am currently reading Dr. Richard Haier's book The Neuroscience of Intelligence. I have a base knowledge of statistics, but I am confused about the following extract from page 80 (chapter 2.4): ...
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1answer
18 views

What is the notation about group differences in terms standard deviations?

I am just getting into watching psych lectures and things online and am taking notes but I have been wondering what the proper/standard way of writing in note form about standard deviations is. For ...
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28 views

What to call variables that measures human's random preferences to select a given experimental stimuli?

I understand that in some cases, given a set of objects, human subjects asked to randomly select one will tend to favor one over others. We all know the situation where "37" will be favored when ...
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Books on Statistics in R for behavioral data analysis

Are there any statistics books geared towards teaching behavioral data analysis especially in psycholinguistics?
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Measuring originality of a person on a sentence completion task

I conducted an experiment where I had 20 people complete 100 sentences with only one word. They had to come up with their completion independently of others and could give any answer they thought was ...
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What is the distinction between “relationship” and “difference” in behavioural statistics?

Quoting [emphasis added] from D.C. Howell's (2012) Statistical Methods for Psychology, chapter 9 (Correlation and Regression), Pg 252: Although you should not make too much of the distinction ...
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Generosity in the World Happiness Score

One factor in the World Happiness Score is generosity. I had trouble to understand what this actually means and how it enters into the score. These were my specific questions: Does "generosity" ...
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1answer
39 views

If a two-tailed test shows significance and the mean is higher, can you infer that one condition is significantly higher?

Condition A has M=5, SD=1 Condition B has M=10, SD=1 If a two-tailed test gives p<.05, can you infer that Condition B was significantly higher than Condition A without conducting a one-tailed ...
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1answer
26 views

Do .sav files expire after the trial version expires?

I saved a certain file on an SPSS software that expires after 2 weeks of its installation. I wanted to ask if my file would still exist even after the expiration date. The data is for psychology ...
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2answers
104 views

correction for multiple comparison over many ROIs

I would like to know how to correct a p value of a stiatistic when the same test was run over multiple regions of interest. The modality is MEG. So, I have 4 Regions Of Interests, and I ran the same ...
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1answer
50 views

Are the raw scores of the NEO-PI-R normally distributed?

Scoring the NEO-PI-R test results, as done for example in this document, involves converting an absolute score to a t-score. However, the conversion from absolute score to t-score (as can be seen in ...
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How many people have a mental disorder in the world at the same time?

According to this article, Mental disorders affect one in four people One in four people in the world will be affected by mental or neurological disorders at some point in their lives But this ...
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1answer
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Independence of criterion and d-prime (psychophysics)

I am reading here, page 5 that d' (d-prime) does not vary with criterion (in contrast to hit rate for instance which does vary with criterion, and which can be a biased measure of a subject's ...
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1answer
88 views

Is there actually a correlation between emotional trauma and homosexuality

One of the key talking points I hear to disparage homosexuality is that it stems from "a lack of a strong male figure" or some variation of that, putting aside the obvious irrelevancy of argument. I ...
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Averaging a linear or nonlinear function treatment

In a hypothetical PET study, my sample consists of a clinical population which exhibit brain hypermetabolism. I divide my sample into two homogenous groups. One receives a treatment whereas the other ...
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2answers
171 views

Bounds on skew and kurtosis of IQ

The question of whether IQ is Normally distributed, or instead follows e.g. a Pearson type IV distribution, has been debated since at least the 1910s. The quotient- and deviation-based definitions ...
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Recommended resources (journals, blogs, etc) for nurturing a background of statistical/methodological rigour in behavioural science research?

Background : There seems to considerable debate regarding the output of psychological research lacking a) appropriate, rigourous statistical treatment of data b) replicability As a second year ...
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Questions on Interpreting Factor Analysis Results and Scores

I am trying to learn factor analysis and I thought it would be a good idea to try and very poorly "mimic" the computation for IQ scores with a dataset of dummy values as a way to "learn by example". ...
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Is it okay to use “fixed number of factors” in EFA after contradicting results from MAP test and eigenvalues?

I need help with my data analysis. I am using a non-validated translated questionnaire in my survey. The purpose of it is not to validate the measure in a different language and its construct validity,...
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1answer
2k views

Is writing ability associated with IQ or intelligence?

Is greater ability to write well i.e. analysis of books/literature/research papers associated with higher I.Q. scores? Statistically speaking, is writing ability normally distributed like I.Q. is?
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Ability of fixed-effects analyses to enable generalisation of results

Is it correct to say that, when making inferrence on the results of an experiment, using a random-effects (RFX) rather than a fixed-effects (FFX) model merely makes the results more generalisable, as ...
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46 views

What statistics can compare individual survey responses & others that were measured as a group (from which we need to extract individual responses)?

The organization I belong to studies indigenous populations through primarily survey research. One study for example aims to identify the relationship between culture and the evaluation of odors. We ...
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81 views

Which experimental design is this? Factorial vs within groups

I have two independent variables (age and gender) and one dependent variable (the results of a questionnaire using a Likert scale). I'm trying to see whether age and/or gender have an effect on the ...
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1answer
37 views

When to use standard versus moderator regression techniques for the most parsimonious approach?

I know how to run multiple regressions (SMR, HMR, and MMR) in SPSS but I'm still a little vague on when it's appropriate to use each of them to achieve the best and most parsimonious result. (SPSS ...
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60 views

How to statistically test whether parents and children share similar humor styles?

I have data from children and their parents on their humor styles (using the Humor Styles Questionnaire by Martin (2003)). For the adult version: It's a 32-item measure, with 4 subscales for each ...
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1answer
121 views

In fMRI analyses, what is the t-test actually comparing?

In a 1st-level fMRI analysis, it is unclear to me what the t-test performed for each voxel is actually comparing. I've seen this being described in one of two different ways: The t-test estimates how ...
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58 views

Statistic analysis on EEG data - how to deal with it properly?

Let's assume that I have a datasheet looking like that: ...
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What does it mean to “control for differences in factors” when looking at gun ownership and homicide rates?

What does it mean "with control for differences in factors" in the sentence : "Several studies used cross-sectional analyses to detect a positive relationship between the prevalence of gun ownership ...
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Task-based fMRI dataset with very simple task (e.g. view stripes)

For my Bachelor thesis I need an fMRI dataset in order to look for causal relationships. I want to be able to confirm my work, so the causal relationships should already be known. Therefore, ideally ...
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1answer
439 views

What does it mean statistically for there to be significant differences in average IQ scores between racial groups?

Charles Murray (in his book, "The Bell Curve") reported that there are real differences between the mean IQ scores of different racial groups. He also points out that IQ variation within said groups ...
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1answer
92 views

What are the benefits of using all 30 personality facets in multiple regressions compared to just including hypothesised facets?

What are the advantages/disadvantages of using all 30 facets (NEO PI-R; Costa & McCrae, 1992) in a multiple regression versus only using the facets that you have a hypothesis for? I see that the ...
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23 views

What is the rule that describes sufficiently large groups will have bad actors?

I once heard of a rule/law/number that described any group sufficiently large enough will have "bad" people in it. It is most often used to describe how online communities will have to deal with ...
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1answer
57 views

What is restriction of range correction formula when you don't know standard deviation of unrestricted group?

What is the restriction of range formula if you don't know the standard deviation of the unrestricted group is? For instance, you run a selection process, 1st stage is a cognitive ability test and ...
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3answers
103 views

Should I look at the data of an experiment before the dataset is complete?

For a research internship I am running psychological experiments online. As it takes a while until the experiment is done (meaning that enough people participated, so that a sufficient sample size is ...
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2answers
220 views

Can people act randomly? [duplicate]

Let's imagine an experiment. We will tell N normal people that they need to act randomly in the Rock–paper–scissors game (in this game Game Optimal Strategy is to choose an action with uniform ...
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1answer
57 views

Calculating statistical significance in behaviour change

I have run a study on a group of 158 individuals to see if a teaching intervention can change their perceptions of scientists. Before the intervention, all the children in the study were asked to ...
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1answer
65 views

Multiple-stratum intelligence models

My question concerns the mathematics of multiple-stratum models, about which I've not found much that's quantitative, so excuse my inventing my own notation to explain my thoughts. In models such as ...
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1answer
746 views

What is the rationale for the normal distribution of intelligence?

What is the rationale for the normal distribution of intelligence? I'm asking what the rationale is for saying that 68% of variance within intelligence falls within 1 standard deviation either side ...
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205 views

Testosterone in women vs. estrogen in men?

It is known that women with higher estrogen are more likely to find men with higher testosterone as more attractive. Positive feedback is also known. But are women with higher testosterone level are ...
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1answer
503 views

Is it possible to calculate the probability of a child having an IQ in a certain range based on their parents' IQ?

For instance, if two parents have IQs of 160, can one calculate the probability that their child has an IQ over 160?
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Does Emotional Intelligence (EQ) demonstrate the Flynn Effect?

The Flynn Effect is a well-known phenomenon whereby Intelligence Quotient (IQ) test scores among the general public seem to rise over time. Does Emotional Intelligence (EQ) demonstrate the Flynn ...
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Examples of interventions that yield large long term effect sizes in psychology

I was listening to a podcast entitled Very Bad Wizards, hosted by two university academics. One of the hosts, namely David Pizarro who is a psychologist at Cornell made the claim that most ...