Figures and Tables Best Practices

Overview

Figures and tables are essential components of scientific papers, serving to display data patterns, summarize results, and provide evidence for conclusions. Effective visual displays enhance comprehension and can sustain reader interest while illustrating trends, patterns, and relationships not easily conveyed through text alone.

A recent Nature Cell Biology checklist (2025) emphasizes that creating clear and engaging scientific figures is crucial for communicating complex data with clarity, accessibility, and design excellence.

When to Use Tables vs. Figures

Use Tables When:

• Presenting precise numerical values that readers need to reference
• Comparing exact measurements across multiple variables
• Showing detailed statistical outputs
• Data cannot be adequately summarized in 1-2 sentences
• Readers need access to specific data points
• Displaying demographic or baseline characteristics
• Presenting multiple related statistical tests

Example use cases:

• Baseline participant characteristics (age, sex, diagnosis, etc.)
• Detailed statistical model outputs (coefficients, p-values, confidence intervals)
• Dose-response data with exact values
• Gene expression levels for specific genes
• Chemical compositions or concentrations

Use Figures When:

• Showing trends over time
• Displaying relationships or correlations
• Comparing groups visually
• Illustrating distributions
• Demonstrating patterns not easily seen in numbers
• Showing images (microscopy, radiography, etc.)
• Displaying workflows, diagrams, or schematics

Example use cases:

• Growth curves or time series
• Dose-response curves
• Scatter plots showing correlations
• Bar graphs comparing treatment groups
• Histograms showing distributions
• Heatmaps displaying patterns across conditions
• Microscopy images or Western blots

General Decision Rule

Can the information be conveyed in 1-2 sentences of text?

• Yes → Use text only
• No, and precise values are needed → Use a table
• No, and patterns/trends are most important → Use a figure

Core Design Principles

1. Self-Explanatory Display Items

Each figure or table must stand alone without requiring the main text.

Essential elements:

• Complete, descriptive caption
• All abbreviations defined (in caption or footnote)
• Units of measurement clearly indicated
• Sample sizes (n) reported
• Statistical significance annotations explained
• Legend included (for figures with multiple data series)

Example of self-explanatory caption:

Figure 1. Mean systolic blood pressure (SBP) over 12 weeks in intervention and control groups.
Error bars represent standard error of the mean (SEM). Asterisks indicate significant
differences between groups at each time point (*p < 0.05, **p < 0.01, ***p < 0.001,
two-tailed t-tests). n = 48 per group. BP = blood pressure; SEM = standard error of mean.

2. Avoid Redundancy

Do not duplicate information between text, tables, and figures.

Bad practice:

"Mean age was 45.2 years in Group A and 47.8 years in Group B. Mean BMI was 26.3 in
Group A and 28.1 in Group B. Mean systolic blood pressure was 132 mmHg in Group A..."
[Also shown in Table 1]

Good practice:

"Baseline characteristics were similar between groups (Table 1), with no significant
differences in age, BMI, or blood pressure (all p > 0.15)."
[Details in Table 1]

Key principle: Text should highlight key findings from tables/figures, not repeat all data.

3. Consistency

Maintain uniform formatting across all display items:

• Font types and sizes
• Color schemes
• Terminology and abbreviations
• Axis labels and units
• Statistical annotation methods
• Figure styles (all line graphs should look similar)

Example of inconsistency to avoid:

• Figure 1 uses "standard error" while Figure 2 uses "SE"
• Figure 1 has blue/red color scheme while Figure 2 uses green/yellow
• Table 1 reports p-values as "p = 0.023" while Table 2 uses "p-value = .023"

4. Optimal Quantity

Follow the "one display item per 1000 words" guideline.

Typical manuscript:

• 3000-4000 words → 3-4 tables/figures total
• 5000-6000 words → 5-6 tables/figures total

Quality over quantity: A few well-designed, information-rich displays are better than many redundant or poorly designed ones.

5. Clarity and Simplicity

Avoid cluttered or overly complex displays:

• Don't include too many variables in one figure
• Use clear, readable fonts (minimum 8-10 pt in final size)
• Provide adequate spacing between elements
• Use high contrast (especially for color-blind accessibility)
• Remove unnecessary grid lines, borders, or decoration
• Maximize data-ink ratio (Tufte principle: minimize non-data ink)

Figure Types and When to Use Them

Bar Graphs

Best for:

• Comparing discrete categories or groups
• Showing counts or frequencies
• Displaying mean values with error bars

Design guidelines:

• Start y-axis at zero (unless showing small differences in large values)
• Order bars logically (by size, alphabetically, or temporally)
• Use error bars (SD, SEM, or CI) consistently
• Include sample sizes
• Avoid 3D effects (they distort perception)

Common mistakes:

• Not starting at zero (can exaggerate differences)
• Too many categories (consider table instead)
• Missing error bars

Example applications:

• Mean gene expression across tissue types
• Treatment group comparisons
• Frequency of adverse events

Line Graphs

Best for:

• Showing trends over continuous variables (usually time)
• Displaying multiple groups on same axes
• Illustrating dose-response relationships

Design guidelines:

• Use different line styles or colors for groups
• Include data point markers for sparse data
• Show error bars or shaded confidence intervals
• Label axes clearly with units
• Use consistent intervals on x-axis

Common mistakes:

• Connecting discrete data points that shouldn't be connected
• Too many lines making graph unreadable
• Inconsistent time intervals without indication

Example applications:

• Growth curves
• Time course experiments
• Survival curves (Kaplan-Meier plots)
• Pharmacokinetic profiles

Scatter Plots

Best for:

• Showing relationships between two continuous variables
• Displaying correlations
• Identifying outliers

Design guidelines:

• Include trend line or regression line with equation and R²
• Report correlation coefficient and p-value
• Use semi-transparent points if data overlap
• Consider logarithmic scales for wide ranges
• Mark outliers if relevant

Common mistakes:

• Not showing individual data points
• Using scatter plots for categorical data
• Missing correlation statistics

Example applications:

• Correlation between biomarkers
• Relationship between dose and response
• Method comparison (Bland-Altman plots)

Box Plots (Box-and-Whisker Plots)

Best for:

• Showing distributions and spread
• Comparing distributions across groups
• Identifying outliers

Design guidelines:

• Clearly define box elements (median, quartiles, whiskers)
• Show or note outliers explicitly
• Consider violin plots for small sample sizes
• Overlay individual data points when n < 20

Common mistakes:

• Not defining what whiskers represent
• Using for very small samples without showing raw data
• Not marking outliers

Example applications:

• Comparing distributions across treatment groups
• Showing variability in measurements
• Quality control data

Heatmaps

Best for:

• Displaying matrices of data
• Showing patterns across many conditions
• Representing clustering or grouping

Design guidelines:

• Use color scales that are perceptually uniform
• Include color scale bar with units
• Consider hierarchical clustering for rows/columns
• Use appropriate color scheme (diverging vs. sequential)
• Make axes labels readable

Common mistakes:

• Poor color choice (rainbow scales are often misleading)
• Too many rows/columns making labels unreadable
• No color scale bar

Example applications:

• Gene expression across samples
• Correlation matrices
• Time-series data across multiple variables

Images (Microscopy, Gels, Blots)

Best for:

• Showing representative examples
• Demonstrating morphology or localization
• Presenting gel electrophoresis or Western blots

Design guidelines:

• Include scale bars (not magnification in caption)
• Show representative images with quantification in separate panel
• Label important features with arrows or labels
• Ensure adequate resolution (usually 300+ dpi)
• Show full, unmanipulated images with cropping noted
• Include all relevant controls

Common mistakes:

• No scale bar
• Over-processed or manipulated images
• Cherry-picking best images without quantification
• Insufficient resolution

Example applications:

• Histological sections
• Immunofluorescence
• Western blots
• Gel electrophoresis

Forest Plots

Best for:

• Displaying meta-analysis results
• Showing effect sizes with confidence intervals
• Comparing multiple studies or subgroups

Design guidelines:

• Include point estimates and CI for each study
• Show overall pooled estimate clearly
• Include line of no effect (typically at 1.0 or 0)
• List study details or weights

Example applications:

• Meta-analyses
• Systematic reviews
• Subgroup analyses

Flow Diagrams

Best for:

• Study participant flow (CONSORT diagrams)
• Systematic review search process (PRISMA diagrams)
• Experimental workflows

Design guidelines:

• Follow reporting guideline templates (CONSORT, PRISMA)
• Use consistent shapes and connectors
• Include numbers at each stage
• Clearly show inclusions and exclusions

Table Design Guidelines

Structure

Basic anatomy:

1. Table number and title (above table)
2. Column headers (with units)
3. Row labels
4. Data cells (with appropriate precision)
5. Footnotes (below table for abbreviations, statistics, notes)

Formatting Best Practices

Column headers:

• Use clear, concise labels
• Include units in parentheses
• Use abbreviations sparingly (define in footnote)

Data presentation:

• Align decimal points in columns
• Use consistent decimal places (usually 1-2 for means)
• Report same precision across rows/columns
• Use en-dash (–) for "not applicable"
• Use appropriate precision (don't over-report)

Statistical annotations:

• Use superscript letters (ᵃ, ᵇ, ᶜ) or symbols (*, †, ‡) for footnotes
• Define p-value thresholds clearly
• Report exact p-values when possible (p = 0.032, not p < 0.05)

Footnotes:

• Define all abbreviations
• Explain statistical tests used
• Note any missing data
• Indicate data source if not original

Example Table Format

Table 1. Baseline Characteristics of Study Participants

Characteristic          Intervention (n=50)   Control (n=48)    p-value
─────────────────────────────────────────────────────────────────────────
Age, years               45.3 ± 8.2           47.1 ± 9.1        0.28
Male sex, n (%)          28 (56)              25 (52)           0.71
BMI, kg/m²               26.3 ± 3.8           27.1 ± 4.2        0.32
Current smoker, n (%)    12 (24)              15 (31)           0.42
Systolic BP, mmHg        132 ± 15             134 ± 18          0.54
─────────────────────────────────────────────────────────────────────────

Data presented as mean ± SD or n (%). p-values from independent t-tests for
continuous variables and χ² tests for categorical variables. BMI = body mass
index; BP = blood pressure; SD = standard deviation.

Common Table Mistakes

1. Excessive complexity (too many rows/columns)
2. Insufficient context (missing units, unclear abbreviations)
3. Over-precision (reporting 5 decimal places for p-values)
4. Missing sample sizes
5. No statistical comparisons when appropriate
6. Inconsistent formatting across multiple tables
7. Duplicate information with figures or text

Statistical Presentation in Figures and Tables

Reporting Requirements

For each comparison, report:

1. Point estimate (mean, median, proportion)
2. Measure of variability (SD, SEM, CI)
3. Sample size (n)
4. Test statistic (t, F, χ², etc.)
5. p-value (exact when p > 0.001)
6. Effect size (when appropriate)

Error Bars

Choose the appropriate measure:

Key rule: Always state which measure is shown.

Example caption:

"Error bars represent 95% confidence intervals."
NOT: "Error bars represent standard error."

Recommendation: 95% CI preferred because non-overlapping CIs indicate significant differences.

Significance Indicators

Common notation:

* p < 0.05
** p < 0.01
*** p < 0.001
n.s. or NS = not significant

Alternative: Show exact p-values in table or caption

Best practice: Define significance indicators in every figure caption or table footnote.

Accessibility Considerations

Color-Blind Friendly Design

Recommendations:

• Use color palettes designed for color-blind accessibility
• Don't rely on color alone (add patterns, shapes, or labels)
• Test figures in grayscale
• Avoid red-green combinations

Color-blind safe palettes:

• Blue-Orange
• Purple-Yellow
• Colorbrewer2.org palettes
• Viridis, Plasma, Inferno (for heatmaps)

High Contrast

Ensure readability:

• Dark text on light background (or vice versa)
• Avoid low-contrast color combinations (gray on gray)
• Use thick enough lines (minimum 0.5-1 pt)
• Large enough text (minimum 8-10 pt after scaling)

Screen and Print Compatibility

Design for both media:

• Use vector formats when possible (PDF, EPS, SVG)
• Minimum 300 dpi for raster images (TIFF, PNG)
• Test appearance at final print size
• Ensure color figures work in grayscale if printed

Technical Requirements

File Formats

Vector formats (preferred for graphs and diagrams):

• PDF: Universal, preserves quality
• EPS: Encapsulated PostScript, publishing standard
• SVG: Scalable vector graphics, web-friendly

Raster formats (for photos and images):

• TIFF: Uncompressed, high quality, large files
• PNG: Lossless compression, good for screen
• JPEG: Lossy compression, avoid for data figures

Avoid:

• Low-resolution screenshots
• Figures copied from presentations (usually too low resolution)
• Heavily compressed JPEGs (artifacts)

Resolution Requirements

Minimum standards:

• Line art (graphs, diagrams): 300-600 dpi
• Halftones (photos, grayscale