Agent skill

Trend Analysis

by benchflow-ai in benchflow-ai/skillsbench

Detect long-term trends in time series data using parametric and non-parametric methods.

MITAuto-check passedData & Analytics

Install Trend Analysis

skills CLI
$ npx skills add benchflow-ai/skillsbench --skill trend-analysis -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install benchflow-ai/skillsbench trend-analysis --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/benchflow-ai/skillsbench.git skills-src && mkdir -p .claude/skills && cp -r skills-src/tasks/lake-warming-attribution/environment/skills/trend-analysis .claude/skills/trend-analysis && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
trend-analysis
GitHub stars
1.8k
Token cost
~697 tokens
SKILL.md length
211 words
Files
1
Skills in repo
178
Repo updated
First seen
Licence
MIT

At a glance

Detect long-term trends in time series data using parametric and non-parametric methods.

  • Determining if a variable shows statistically significant increase
  • SKILL.md covers Overview, Parametric Method: Linear…, Non-Parametric Method: Sen's… and Significance Levels, plus 3 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Decrease over time

What it does

Trend Analysis is an agent skill from benchflow-ai/skillsbench. Detect long-term trends in time series data using parametric and non-parametric methods. Use when determining if a variable shows statistically significant increase or decrease over time.

Its SKILL.md is about 700 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Data & Analytics, covering Forecasting and time series. The repository describes itself as: SkillsBench evaluates how well skills work and how effective agents are at using them. The licence is MIT.

When your agent uses it

  • Determining if a variable shows statistically significant increase
  • Decrease over time

Example prompts

  • “/trend-analysis”

Requirements

  • Python 3

What it can do on your machine

Read from SKILL.md and the folder at commit 9a1f4dd. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are python).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Trend Analysis loads about 697 tokens when it runs. Until then it costs about 51 tokens; SKILL.md has 211 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~51
When it runs · the whole SKILL.md, loaded when a task matches
~697

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from benchflow-ai/skillsbench at commit 9a1f4dd, republished under its MIT licence (© benchflow-ai). 211 words, ~697 tokens.

Download SKILL.mdSave it as .claude/skills/trend-analysis/SKILL.md (or your agent's skills folder).
name
trend-analysis
description
Detect long-term trends in time series data using parametric and non-parametric methods. Use when determining if a variable shows statistically significant increase or decrease over time.
license
MIT

Trend Analysis Guide

Overview

Trend analysis determines whether a time series shows a statistically significant long-term increase or decrease. This guide covers both parametric (linear regression) and non-parametric (Sen's slope) methods.

Parametric Method: Linear Regression

Linear regression fits a straight line to the data and tests if the slope is significantly different from zero.

python
from scipy import stats

slope, intercept, r_value, p_value, std_err = stats.linregress(years, values)

print(f"Slope: {slope:.2f} units/year")
print(f"p-value: {p_value:.2f}")
Assumptions
  • Linear relationship between time and variable
  • Residuals are normally distributed
  • Homoscedasticity (constant variance)

Non-Parametric Method: Sen's Slope with Mann-Kendall Test

Sen's slope is robust to outliers and does not assume normality. Recommended for environmental data.

python
import pymannkendall as mk

result = mk.original_test(values)

print(result.slope)  # Sen's slope (rate of change per time unit)
print(result.p)      # p-value for significance
print(result.trend)  # 'increasing', 'decreasing', or 'no trend'
Comparison
MethodProsCons
Linear RegressionEasy to interpret, gives R²Sensitive to outliers
Sen's SlopeRobust to outliers, no normality assumptionSlightly less statistical power

Significance Levels

p-valueInterpretation
p < 0.01Highly significant trend
p < 0.05Significant trend
p < 0.10Marginally significant
p >= 0.10No significant trend

Example: Annual Precipitation Trend

python
import pandas as pd
import pymannkendall as mk

# Load annual precipitation data
df = pd.read_csv('precipitation.csv')
precip = df['Precipitation'].values

# Run Mann-Kendall test
result = mk.original_test(precip)
print(f"Sen's slope: {result.slope:.2f} mm/year")
print(f"p-value: {result.p:.2f}")
print(f"Trend: {result.trend}")

Common Issues

IssueCauseSolution
p-value = NaNToo few data pointsNeed at least 8-10 years
Conflicting resultsMethods have different assumptionsTrust Sen's slope for environmental data
Slope near zero but significantLarge sample sizeCheck practical significance

Best Practices

  • Use at least 10 data points for reliable results
  • Prefer Sen's slope for environmental time series
  • Report both slope magnitude and p-value
  • Round results to 2 decimal places

© benchflow-ai, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in tasks/lake-warming-attribution/environment/skills/trend-analysis of benchflow-ai/skillsbench.

Open the folder on GitHubat commit 9a1f4dd

Compare with similar skills

Trend Analysis next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Trend Analysis compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Trend Analysis this skillbenchflow-ai/skillsbench1.8k—~697Automated safety check: PassMIT
TimesFM Forecastinggoogle-research/timesfm34k—~4.7kAutomated safety check: PassApache-2.0
Timesfm ForecastingzLanqing/codex-claude-academic-skills4.6k6 repos~7.5kAutomated safety check: NotesApache-2.0
StatsmodelszLanqing/codex-claude-academic-skills4.6k16 repos~4.9kAutomated safety check: PassBSD-3-Clause
Alphaear Predictorninehills/skills2812 repos~531Automated safety check: PassNone
Find Hypertable Candidatestimescale/pg-aiguide1.9k1 repos~2.6kAutomated safety check: PassApache-2.0

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Questions about Trend Analysis

What does Trend Analysis do?

Detect long-term trends in time series data using parametric and non-parametric methods. Trend Analysis is an agent skill from benchflow-ai/skillsbench. Detect long-term trends in time series data using parametric and non-parametric methods.

When should I use Trend Analysis?

Trend Analysis fits situations like: determining if a variable shows statistically significant increase; decrease over time.

How do I install Trend Analysis in Claude Code?

Run `npx skills add benchflow-ai/skillsbench --skill trend-analysis -a claude-code`. Or copy the skill folder (tasks/lake-warming-attribution/environment/skills/trend-analysis in benchflow-ai/skillsbench) into .claude/skills/trend-analysis in your project. Claude Code loads it when a task matches its description.

How do I install Trend Analysis in Codex?

Run `npx skills add benchflow-ai/skillsbench --skill trend-analysis -a codex`. Or copy the skill folder (tasks/lake-warming-attribution/environment/skills/trend-analysis in benchflow-ai/skillsbench) into .agents/skills/trend-analysis in your project. Codex loads it when a task matches its description.

Can I use Trend Analysis in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add benchflow-ai/skillsbench --skill trend-analysis -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/trend-analysis, .gemini/skills/trend-analysis, .github/skills/trend-analysis and .opencode/skills/trend-analysis in your project.

What does Trend Analysis need to run?

SKILL.md names no scripts, command-line tools or credentials: Trend Analysis is instructions for the agent only. Our summary lists: Python 3.

Does Trend Analysis access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Trend Analysis safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Trend Analysis use?

Trend Analysis is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Trend Analysis use?

About 697 tokens (SKILL.md is roughly 2.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Trend Analysis?

Skills that share tags, products or a category with Trend Analysis: TimesFM Forecasting (google-research/timesfm, 34k stars), Timesfm Forecasting (zLanqing/codex-claude-academic-skills, 4.6k stars), Statsmodels (zLanqing/codex-claude-academic-skills, 4.6k stars) and Alphaear Predictor (ninehills/skills, 281 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Trend Analysis?

benchflow-ai (a GitHub organization) maintains it in benchflow-ai/skillsbench, which has 1,832 GitHub stars. The repository holds 178 skills in this directory. The repository was last updated on July 23, 2026.

Source: benchflow-ai/skillsbench on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.