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One small, psychological ANOVA example you can use in class.

This is just a little one-way ANOVA with three levels. You can use it in class to assess, review, or teach the topic. It comes from the following article by Rivera-Chavez et al.


https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2843427


TL:DR- They gathered data and performed a one-way ANOVA that suggests that people with emerging psychosis have glutamate (a neurotransmitter) levels that are higher than both controls and folks who have schizophrenia diagnoses.

Even if you aren't an expert on this topic, JAMA's ready to explain the relevance of this study to your students:

Conclusions and Relevance  These findings suggest that the differences in glutamate levels may indicate that these alterations occur primarily in the early stages of the disease. The results of this study have implications for resuming clinical trials with targeted metabotropic glutamate receptor 2/3 agonists, taking into account both the disease phase and the glutamatergic alterations measured by magnetic resonance imaging.

Text reads: Key Points Question  What is the temporal nature of glutamate alterations at different stages of the schizophrenia spectrum as revealed by using proton magnetic resonance spectroscopy?  Findings  This cross-sectional study reports prefrontal glutamate levels in 83 never-medicated individuals with psychosis with varying durations of illness and 60 controls. There were significant elevations of glutamate level in individuals classified as having first-episode psychosis compared with both individuals with chronic schizophrenia and controls.  Meaning  These findings suggest that early-stage schizophrenia is associated with elevated prefrontal glutamate levels, making it a target for compounds that reduce glutamatergic transmission and therapeutic potential.

Reasons why I love this as an example for my novice psychological statisticians:

1. This data is related to psychology, a simple one-way ANOVA with three levels, and was recently published, making it a nice little refresh to my course content.

There are other analyses in the article, but here are the ANOVA results.

Glutamate levels differed among the 3 groups (F2,136 = 7.5; P = .001). Post hoc pairwise comparisons revealed higher glutamate levels in the FEP group compared with both the chronic schizophrenia group (P = .003; Cohen d = 0.69) and the control group (P = .008; Cohen d = 0.83). There were no significant differences in glutamate levels between the chronic schizophrenia group and the control group (P > .99). Higher glutamate levels were associated with lower verbal (ρ = −0.29; P = .04) and visual learning scores (ρ = −0.29; P = .04) in the FEP group.

2. I emphasize that my students learn how to read and write statistical findings, so here are a few of the questions I'll ask my students after they read the text I copied and pasted above:

-What is the factor? What are the levels?

-What was the overall p-value for the ANOVA?

-According to the post-hoc, what was pulling the significance? 

3. Data is presented with a jitter plot. I'm so over bar graphs. Show me the variability, participant by participant. I also like the brain image that shows the exact portion of the brain being studied. 

4. This data isn't WEIRD. It is from a team in Mexico with a sample drawn from a Mexican hospital.









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