Higher Headache Severity Predicts Moderately Higher Tiredness / Fatigue for Population

Higher Headache Severity Predicts Moderately Higher Tiredness / Fatigue for Population

Contents

Variables

A
Headache Severity 1498
A
Tiredness / Fatigue 1606

Categories

A
Symptoms 13336
A
Symptoms 13336

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Your Data

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High Confidence
Weak Effect Size
Positive Relationship
Population Study
cause image gauge image effect image
Participants reported a 14% average increase in Tiredness / Fatigue following above average Headache Severity.

Abstract

Tiredness / Fatigue was generally 17.8846% higher than average after 2.33 out of 5 of Headache Severity per 24 hours.

Aggregated data from 13 study participants suggests with a HIGH degree of confidence (p=0.143, 95% CI -0.121 to 0.766) that Headache Severity has a moderately positive predictive relationship (R=0.323) with Tiredness / Fatigue.

The highest quartile of Tiredness / Fatigue measurements were observed following an average 2.71 out of 5 Headache Severity.

The lowest quartile of Tiredness / Fatigue measurements were observed following an average 2.32 out of 5 of Headache Severity.

After an onset delay of 0 seconds, Tiredness / Fatigue is typically 6% lower than average over the 24 hours following around 2.32 out of 5 of Headache Severity Headache Severity.

Keywords: Headache Severity, Tiredness / Fatigue, N-of-1 trials, real-world evidence, causal inference, observational study

Moderate Confidence: Based on 13 participants. More data would increase certainty.

Results

Primary Findings

Analysis of 1,503 paired observations from 13 participants revealed a moderate improvement in Tiredness / Fatigue following above-average Headache Severity exposure.

+17.9%
Change from Baseline
Moderate effect on Tiredness / Fatigue
0.23
Predictor Impact Score
Weak evidence for causal relationship

Supporting Statistics

High
Confidence
0.323
Correlation (r)
p = 0.402
Significance
z = 0.70
Effect Magnitude
φ = 1.00
Temporality

What This Means

When participants had above-average Headache Severity:

  • Tiredness / Fatigue increased by 17.9% on average
  • Temporal analysis supports Headache Severity as the predictor (not the outcome)

Interpreting the Predictor Impact Score

The Predictor Impact Score (PIS) integrates multiple Bradford Hill causal criteria into a single metric. Use this guide to interpret the score:

PIS Range Interpretation Recommended Action
≥ 0.5 Strong evidence High priority for RCT validation
0.3 - 0.5 Moderate evidence Consider for experimental investigation
0.1 - 0.3 Weak evidence Monitor for additional data
< 0.1 Insufficient evidence Low priority; may be noise

Note: PIS is a prioritization heuristic, not proof of causation. High scores indicate relationships worth investigating, not confirmed causal effects. With only 13 participants, these scores are preliminary and will become more reliable as additional data is collected.

Optimal Daily Values (Precision Dosing)

Based on the observed relationship, we can estimate the predictor values associated with the best and worst outcomes. These values enable personalized dosing recommendations.

⚠️ Preliminary Data: With 13 participants and 1,503 observations, these optimal values are preliminary estimates. As more data is collected, precision will improve significantly.

3.1 /5
Value Predicting Higher Tiredness / Fatigue
Average Headache Severity when Tiredness / Fatigue exceeded its mean
2.3 /5
Value Predicting Lower Tiredness / Fatigue
Average Headache Severity when Tiredness / Fatigue was below its mean

What This Suggests

Tiredness / Fatigue tended to be highest when Headache Severity was around 3.1 /5.

Important: These values reflect correlations, not guaranteed causal effects. Individual responses may vary. Use as a starting point for personal experimentation, not as a definitive prescription. Consult healthcare providers before making treatment decisions.

Population Correlation

Headache Severity Distribution

Tiredness / Fatigue Distribution

Relationship Analysis

Statistical Summary

Relationship Statistics

Property Value
Cause Variable Name Headache Severity
Effect Variable Name Tiredness / Fatigue
Sinn Predictive Coefficient 0.23460848980885
Confidence Level HIGH
Confidence Interval 0.44393202789784
Forward Pearson Predictive Coefficient 0.3225
Critical T Value 1.7251538461538
Average Headache Severity Over Previous 24 hours Before ABOVE Average Tiredness / Fatigue 2.71 out of 5
Average Headache Severity Over Previous 24 hours Before BELOW Average Tiredness / Fatigue 2.32 out of 5
Duration of Action 24 hours
Effect Size moderately positive
Number of Paired Measurements 1503
Optimal Pearson Product 0.28548021845076
P Value 0.14338611655033
Statistical Significance 0.4016
Strength of Relationship 0.44393202789784
Study Type population
Analysis Performed At 2026-01-04
Number of Participants 13

Headache Severity Info

Property Value
Variable Name Headache Severity
Aggregation Method MEAN
Analysis Performed At 2021-04-22
Duration of Action 24 hours
Kurtosis 2.6188505753424
Maximum Allowed Value 5 out of 5
Mean 2.7185156626506 out of 5
Median 2.6872903614458 out of 5
Minimum Allowed Value 1 out of 5
Number of Aggregate Predictors 1317
Number of Aggregate Outcomes 181
Number of Measurements 5408
Number of Measurements (including those generated by tagged, joined, or child variables) 5408
Public true
Onset Delay 0 seconds
Standard Deviation 0.41171668487351
Unit 1 to 5 Rating
User Variables 351
UPC 0
Variable Category Symptoms
Variable ID 87323
Variance 0.48864093917025

Tiredness / Fatigue Info

Property Value
Variable Name Tiredness / Fatigue
Aggregation Method MEAN
Analysis Performed At 2022-08-24
Duration of Action 24 hours
Kurtosis 1.6919668468584
Maximum Allowed Value 5 out of 5
Mean 3.3804466501241 out of 5
Median 3.3840182382134 out of 5
Minimum Allowed Value 1 out of 5
Number of Aggregate Predictors 1322
Number of Aggregate Outcomes 284
Number of Measurements 8649
Number of Measurements (including those generated by tagged, joined, or child variables) 8649
Public true
Onset Delay 0 seconds
Standard Deviation 0.35915630620121
Unit 1 to 5 Rating
User Variables 1231
UPC 635797687433
Variable Category Symptoms
Variable ID 87760
Variance 0.38608734381768

Introduction

Background

Headache Severity (Symptoms) and Tiredness / Fatigue (Symptoms) are both important factors in understanding human health and well-being. This study investigates the relationship between these two variables using real-world observational data.

Traditional randomized controlled trials (RCTs), while the gold standard for causal inference, are often impractical, expensive, or unethical for studying many health relationships. Aggregated N-of-1 observational studies offer a complementary approach that leverages within-subject comparisons across large populations to identify meaningful patterns.

Research Question

Does Headache Severity affect Tiredness / Fatigue?

Additionally, we seek to determine:

  1. What is the direction and magnitude of any effect?
  2. How confident can we be in this relationship based on the available data?
  3. What are the optimal levels of Headache Severity for maximizing Tiredness / Fatigue?

Study Objective

The objective of this study is to determine the nature of the relationship (if any) between Headache Severity and Tiredness / Fatigue. Additionally, we attempt to determine the Headache Severity values most likely to produce optimal Tiredness / Fatigue values.

Study Overview

This is a population-level observational study using aggregated N-of-1 methodology. By aggregating individual N-of-1 experiments, we can identify population-level patterns while accounting for the substantial individual variation that exists in most health relationships. Effect sizes are reported as percent change from baseline, enabling intuitive interpretation and comparison across different measures.

Full Methodology: Framework for Real-World Evidence-Based Pharmacovigilance: Aggregated N-of-1 Trials for Quantifying Treatment Effects

Discussion

Interpretation of Findings

Participants experienced a 17.9% improvement in Tiredness / Fatigue following above-average Headache Severity exposure. The Predictor Impact Score (PIS) of 0.23 indicates weak evidence for a causal relationship.

Statistical Significance

Using a two-tailed t-test with alpha = 0.05, it was determined that the change in Tiredness / Fatigue is statistically significant at a 95% confidence interval. The p-value of 0.4016 indicates there is less than a 40.16% probability that this result occurred by chance.

After treatment, a 14% increase (0.456 out of 5) from the mean baseline 2.89 out of 5 was observed. The relative standard deviation at baseline was 25.5154%. The observed change was 0.704683 times the standard deviation.

A common rule of thumb considers a change greater than twice the baseline standard deviation on two separate pre-post experiments may be considered significant. This occurrence would have only a 5% likelihood of resulting from random fluctuation (a p-value < 0.05).

T-Test Details
Observed t-value: 2.470
Critical t-value: 1.725

Since t = 2.47 > 1.73, we reject the null hypothesis.

Biological Plausibility

A plausible bio-chemical mechanism between predictor and outcome is critical for interpreting observational findings. This is where human judgment excels beyond statistical analysis.

Community feedback on the biological plausibility of this relationship is still being collected. Consider the known mechanisms by which Headache Severity might influence Tiredness / Fatigue.

Bradford Hill Criteria Assessment

The Bradford Hill criteria provide a framework for assessing causality in observational studies. Our methodology operationalizes six of the nine criteria through the Predictor Impact Score (PIS):

Criterion How Addressed Metric
Strength Effect size magnitude Percent change from baseline (Δ%), z-score
Consistency Cross-participant replication Number of users (N), number of pairs (n)
Temporality Predictor precedes outcome Temporality factor (φ), onset delay (δ > 0)
Biological Gradient Dose-response relationship Gradient coefficient (φgradient)
Plausibility Biological mechanism assessment Community votes on mechanism plausibility
Specificity Category appropriateness Interest factor (finterest)

Predictor Impact Score (PIS)

The PIS integrates multiple Bradford Hill criteria into a composite metric quantifying how reliably a predictor affects an outcome. Higher scores indicate stronger evidence:

Population-Level PIS:

$$\text{PIS}_{\text{agg}} = |r_{\text{forward}}| \cdot w \cdot \phi_{\text{users}} \cdot \phi_{\text{pairs}} \cdot \phi_{\text{change}} \cdot \phi_{\text{gradient}}$$

Where φ-factors are saturation functions approaching 1 as evidence accumulates:

  • φusers = 1 - e-N/10 (user saturation)
  • φpairs = 1 - e-n/nsig (pair saturation)
  • φchange = 1 - e-Δspread/Δsig (effect spread saturation)
  • w = weighted average of plausibility votes

Temporality Assessment

We assess evidence for correct causal direction using the temporality factor:

$$\phi_{\text{temporal}} = \frac{|r_{\text{forward}}|}{|r_{\text{forward}}| + |r_{\text{reverse}}|}$$

Values approaching 1 indicate the predictor precedes the outcome (supporting causation); values near 0.5 suggest ambiguous directionality; values near 0 suggest reverse causation or confounding by indication.

Limitations

As with any observational study, correlation does not prove causation. Key limitations include:

  • Unmeasured confounders: Variables not tracked may influence results
  • Self-selection bias: Health trackers may differ from the general population
  • Measurement error: Self-reported data may contain recall bias
  • Confounding by indication: Sicker individuals may use more treatments

However, within-subject comparison and temporal precedence analysis partially mitigate these limitations. If the relationship is merely coincidental, as participants independently modify their Headache Severity values, the observed strength will decline over time. Spurious correlations naturally dissipate as more data is collected.

Future Directions

Future research should examine:

  • Subgroup analyses to identify individual differences in response
  • Potential confounders and mediators of the observed relationship
  • Optimal dosing and timing for Headache Severity
  • Confirmation through prospective or randomized designs
  • Biological mechanisms underlying the observed effects

Conclusion

📊 Preliminary Findings: With 13 participants, these results are based on limited data. Effect sizes and confidence will improve as more participants contribute data. Consider these findings directional rather than definitive.

Above-average Headache Severity was associated with a 17.9% improvement in Tiredness / Fatigue—a moderate effect. The Predictor Impact Score of 0.23 indicates this relationship is warranting continued monitoring.

Bottom Line: Based on a PIS of 0.23 and a 17.9% effect size, this relationship shows weak evidence. Additional observational data is recommended before investing in experimental validation. Note: These conclusions may strengthen or change direction as more data is collected.

These findings contribute to our understanding of how Headache Severity may influence Tiredness / Fatigue in real-world conditions. While preliminary, these results may inform future research directions. As more participants contribute data, the reliability and precision of these findings will improve substantially.

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Methods

Study Design

This study is based on data donated by 13 participants. Thus, the study design is equivalent to the aggregation of 13 separate n=1 observational natural experiments.

This within-subject design is powerful because it controls for all stable individual characteristics (genetics, baseline health status, socioeconomic factors) that might otherwise confound the relationship between variables.

Data Analysis

Temporal Assumptions

The analysis incorporates temporal assumptions about the relationship between variables:

  • Onset Delay: It was assumed that 0 seconds would pass before a change in Headache Severity would produce an observable change in Tiredness / Fatigue.
  • Duration of Action: It was assumed that Headache Severity could produce an observable change in Tiredness / Fatigue for as much as 24 hours after the stimulus event.

Statistical Methods

For each participant, we calculated the Pearson correlation coefficient between Headache Severity values and subsequent Tiredness / Fatigue values. Individual correlations were then aggregated using Fisher's z-transformation to produce a population-level estimate:

Individual Correlation:

$$r_i = \frac{\sum(x_{ij} - \bar{x}_i)(y_{ij} - \bar{y}_i)}{\sqrt{\sum(x_{ij} - \bar{x}_i)^2 \sum(y_{ij} - \bar{y}_i)^2}}$$

Fisher's Z-Transformation:

$$z_i = \frac{1}{2} \ln\left(\frac{1 + r_i}{1 - r_i}\right)$$

Aggregated Correlation:

$$\bar{r} = \tanh(\bar{z}) \quad \text{where} \quad \bar{z} = \frac{1}{N}\sum_{i=1}^{N} z_i$$

Effect Size Calculation

Effect sizes are reported as percent change from baseline. For each participant, we compare the outcome following above-average predictor values to the overall baseline outcome:

$$\Delta\%_{\text{baseline}} = \frac{\bar{O}_{\text{follow-up}} - \bar{O}_{\text{baseline}}}{\bar{O}_{\text{baseline}}} \times 100$$

Effect Magnitude (Z-Score)

To assess effect magnitude relative to natural variability, we calculate the z-score:

$$z = \frac{|\Delta\%_{\text{baseline}}|}{\text{RSD}_{\text{baseline}}}$$

where RSDbaseline is the relative standard deviation of outcome during baseline period

A z-score > 2 indicates statistical significance (p < 0.05), meaning the observed change exceeds typical baseline fluctuation and is unlikely due to random variation.

Statistical Significance

Correlation significance is assessed using a two-tailed t-test:

$$t = \frac{r\sqrt{n-2}}{\sqrt{1-r^2}}$$

We reject the null hypothesis (ρ = 0) at α = 0.05 when |t| exceeds the critical value, providing statistical evidence that the observed relationship is not due to chance.

Data Sources

Headache Severity data was primarily collected using QuantiModo. QuantiModo allows you to easily track mood, symptoms, or any outcome you want to optimize in a fraction of a second. You can also import your data from over 30 other apps and devices. QuantiModo then analyzes your data to identify which hidden factors are most likely to be influencing your mood or symptoms.

Tiredness / Fatigue data was primarily collected using QuantiModo. QuantiModo allows you to easily track mood, symptoms, or any outcome you want to optimize in a fraction of a second. You can also import your data from over 30 other apps and devices. QuantiModo then analyzes your data to identify which hidden factors are most likely to be influencing your mood or symptoms.

Data Quality

Data quality measures were applied to ensure reliable results:

  • Minimum Data Requirement: Only participants with sufficient paired observations were included in the analysis.
  • Outlier Handling: Extreme values were winsorized to reduce the influence of measurement errors.
  • Missing Data: Days with missing values were handled using appropriate filling strategies based on the variable type.
  • Test User Exclusion: Test accounts and invalid users were excluded from all analyses.

Principal Investigator

Program & Methods

Mike P. Sinn
Sinn, M. P.

Designed and implemented data collection, aggregation, causal inference pipeline, and automated study generation framework. Developed the Predictor Impact Score methodology operationalizing Bradford Hill criteria for ranking causal relationships in observational data. When he tells people this at parties, they usually say they have to go check on their car.

Individual study outputs are automated, reproducible, and open to external audit. (Which I would seriously recommend.)

Contact

Cite This Study

APA Format
Sinn, M. P. (2026). Causal Analysis: Does Headache Severity Affect Tiredness / Fatigue?. The Journal of Citizen Science. https://studies.crowdsourcingcures.org/study/cause-87323-effect-87760-population-study
BibTeX 
@misc{sinn_cause_87323_effect_87760_population_study_2026,
  author = {Sinn, Mike P.},
  title = {Causal Analysis: Does Headache Severity Affect Tiredness / Fatigue?},
  year = {2026},
  publisher = {The Journal of Citizen Science},
  url = {https://studies.crowdsourcingcures.org/study/cause-87323-effect-87760-population-study},
  note = {Accessed: January 6, 2026}
}
Chicago/Turabian
Sinn, Mike P. "Causal Analysis: Does Headache Severity Affect Tiredness / Fatigue?." The Journal of Citizen Science. Accessed January 6, 2026. https://studies.crowdsourcingcures.org/study/cause-87323-effect-87760-population-study.
Harvard
Sinn, M.P., 2026. Causal Analysis: Does Headache Severity Affect Tiredness / Fatigue?. [Aggregated N-of-1 Study] The Journal of Citizen Science. Available at: https://studies.crowdsourcingcures.org/study/cause-87323-effect-87760-population-study [Accessed January 6, 2026].

Study Type: Aggregated N-of-1 Observational Mega-Study
Evidence Level: Level II (Real-World Evidence)
Methodology: Bradford Hill Criteria with Predictor Impact Score (PIS)

References

This framework was originally developed in 2013 based on the Bradford Hill criteria. Subsequent literature has independently validated similar approaches to causal inference from observational data:

  1. Hill, A.B. (1965). The environment and disease: association or causation? Proceedings of the Royal Society of Medicine, 58(5), 295-300. [Bradford Hill criteria]
  2. Lillie, E.O., et al. (2011). The n-of-1 clinical trial: the ultimate strategy for individualizing medicine? Personalized Medicine, 8(2), 161-173. [N-of-1 methodology]
  3. Pearl, J. (2009). Causality: Models, Reasoning, and Inference . Cambridge University Press. [Causal inference]
  4. Hernán, M.A., & Robins, J.M. (2020). Causal Inference: What If . Chapman & Hall/CRC. [Free textbook]
  5. FDA (2018). Framework for FDA's Real-World Evidence Program . U.S. Food and Drug Administration. [Regulatory context]
  6. Duan, N., et al. (2013). Single-patient (n-of-1) trials: a pragmatic clinical decision methodology . Journal of Clinical Epidemiology, 66(8), S21-S28.
  7. Platt, R., et al. (2018). The FDA Sentinel Initiative—an evolving national resource . New England Journal of Medicine, 379(22), 2091-2093.

This information is for research and educational purposes only, not medical advice. Consult a healthcare provider before making health decisions. Terms of Service

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