R. Heller

1. Descriptive Statistics in R

Sun, 01 Mar 2026 00:00:00 +0000

Descriptive statistics give you a first look at your data. Before running any model, you need to understand the shape, centre, and spread of your variables.

Setup Link to heading

library(tidyverse)

# We'll use the built-in mtcars dataset
data(mtcars)
head(mtcars)

Measures of Central Tendency Link to heading

Mean, Median, Mode Link to heading

# Mean
mean(mtcars$mpg)

# Median
median(mtcars$mpg)

# Mode (no built-in function)
get_mode <- function(x) {
 ux <- unique(x)
 ux[which.max(tabulate(match(x, ux)))]
}
get_mode(mtcars$cyl)

When to use which? Link to heading

Measure	Best for	Sensitive to outliers?
Mean	Symmetric distributions	Yes
Median	Skewed distributions	No
Mode	Categorical data	No

Measures of Dispersion Link to heading

# Standard deviation
sd(mtcars$mpg)

# Variance
var(mtcars$mpg)

# Range
range(mtcars$mpg)
diff(range(mtcars$mpg))

# Interquartile range
IQR(mtcars$mpg)

# Quantiles
quantile(mtcars$mpg, probs = c(0.25, 0.5, 0.75))

Summary Statistics at a Glance Link to heading

# Base R summary
summary(mtcars$mpg)

# More detailed summary with psych package
# install.packages("psych")
library(psych)
describe(mtcars$mpg)

Frequency Tables Link to heading

# For categorical/discrete variables
table(mtcars$cyl)

# Proportions
prop.table(table(mtcars$cyl))

# Cross-tabulation
table(mtcars$cyl, mtcars$gear)

Group-wise Summaries Link to heading

mtcars %>%
 group_by(cyl) %>%
 summarise(
 n = n(),
 mean_mpg = mean(mpg),
 sd_mpg = sd(mpg),
 median_mpg = median(mpg),
 min_mpg = min(mpg),
 max_mpg = max(mpg)
 )

Checking Normality Link to heading

# Shapiro-Wilk test
shapiro.test(mtcars$mpg)

# Q-Q plot
qqnorm(mtcars$mpg)
qqline(mtcars$mpg, col = "red")

Skewness and Kurtosis Link to heading

library(moments)
# install.packages("moments")

skewness(mtcars$mpg)
kurtosis(mtcars$mpg)

A skewness near 0 indicates symmetry. Kurtosis near 3 indicates a normal-like tail weight (excess kurtosis near 0).

2. Data Visualisation with ggplot2

Thu, 05 Mar 2026 00:00:00 +0000

Good visualisation is the backbone of data analysis. R’s ggplot2 package implements the grammar of graphics, giving you a flexible, layered system for building any plot you can imagine.

Setup Link to heading

library(tidyverse)
data(mtcars)
mtcars$cyl <- factor(mtcars$cyl)

The Grammar of Graphics Link to heading

Every ggplot has three essential components:

Data — the data frame
Aesthetics (aes()) — mappings from variables to visual properties
Geometries (geom_*) — the type of plot

ggplot(data = mtcars, aes(x = mpg)) +
 geom_histogram(binwidth = 2, fill = "steelblue", colour = "white") +
 labs(title = "Distribution of MPG", x = "Miles per Gallon", y = "Count") +
 theme_minimal()

Histogram and Density Plots Link to heading

# Density plot
ggplot(mtcars, aes(x = mpg, fill = cyl)) +
 geom_density(alpha = 0.5) +
 labs(title = "MPG Density by Cylinder Count", fill = "Cylinders") +
 theme_minimal()

Boxplots Link to heading

ggplot(mtcars, aes(x = cyl, y = mpg, fill = cyl)) +
 geom_boxplot(outlier.colour = "red") +
 labs(title = "MPG by Number of Cylinders", x = "Cylinders", y = "MPG") +
 theme_minimal() +
 theme(legend.position = "none")

Violin Plots Link to heading

ggplot(mtcars, aes(x = cyl, y = mpg, fill = cyl)) +
 geom_violin(trim = FALSE) +
 geom_jitter(width = 0.1, alpha = 0.5) +
 labs(title = "MPG Distribution by Cylinders") +
 theme_minimal() +
 theme(legend.position = "none")

Scatterplots Link to heading

ggplot(mtcars, aes(x = wt, y = mpg, colour = cyl)) +
 geom_point(size = 3) +
 geom_smooth(method = "lm", se = TRUE) +
 labs(
 title = "Weight vs. MPG",
 x = "Weight (1000 lbs)",
 y = "Miles per Gallon",
 colour = "Cylinders"
 ) +
 theme_minimal()

Bar Charts Link to heading

# Count-based
ggplot(mtcars, aes(x = cyl, fill = cyl)) +
 geom_bar() +
 labs(title = "Number of Cars by Cylinder Count") +
 theme_minimal() +
 theme(legend.position = "none")

# Summary-based
mtcars %>%
 group_by(cyl) %>%
 summarise(mean_mpg = mean(mpg), se = sd(mpg) / sqrt(n())) %>%
 ggplot(aes(x = cyl, y = mean_mpg, fill = cyl)) +
 geom_col() +
 geom_errorbar(aes(ymin = mean_mpg - se, ymax = mean_mpg + se), width = 0.2) +
 labs(title = "Mean MPG by Cylinders (± SE)") +
 theme_minimal() +
 theme(legend.position = "none")

Faceted Plots Link to heading

ggplot(mtcars, aes(x = wt, y = mpg)) +
 geom_point() +
 geom_smooth(method = "lm") +
 facet_wrap(~ cyl, scales = "free") +
 labs(title = "Weight vs. MPG by Cylinder Count") +
 theme_minimal()

Correlation Heatmap Link to heading

library(reshape2)

cor_matrix <- cor(mtcars[, sapply(mtcars, is.numeric)])
melted_cor <- melt(cor_matrix)

ggplot(melted_cor, aes(x = Var1, y = Var2, fill = value)) +
 geom_tile() +
 scale_fill_gradient2(low = "blue", high = "red", mid = "white", midpoint = 0) +
 labs(title = "Correlation Heatmap") +
 theme_minimal() +
 theme(axis.text.x = element_text(angle = 45, hjust = 1))

Customising Themes Link to heading

# Create a custom theme for publications
theme_publication <- function() {
 theme_minimal() +
 theme(
 text = element_text(family = "sans", size = 12),
 plot.title = element_text(face = "bold", size = 14),
 axis.title = element_text(face = "bold"),
 legend.position = "bottom",
 panel.grid.minor = element_blank()
 )
}

# Apply it
ggplot(mtcars, aes(x = wt, y = mpg)) +
 geom_point(aes(colour = cyl), size = 3) +
 labs(title = "Publication-Ready Scatterplot") +
 theme_publication()

Saving Plots Link to heading

p <- ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point() + theme_minimal()
ggsave("my_plot.png", p, width = 8, height = 5, dpi = 300)
ggsave("my_plot.pdf", p, width = 8, height = 5)

Key Takeaways Link to heading

Use ggplot2 for all your plotting needs — it is the gold standard in R.
Build plots in layers: data → aesthetics → geometry → labels → theme.
Use facets for multi-panel plots comparing groups.
Create a custom theme for consistent, publication-ready figures.

Previous: ← Descriptive Statistics Next: Inferential Statistics →

3. Inferential Statistics in R

Sun, 08 Mar 2026 00:00:00 +0000

Inferential statistics let you draw conclusions about a population based on sample data. This tutorial covers the most common hypothesis tests and when to use each one.

Setup Link to heading

library(tidyverse)
data(mtcars)
mtcars$cyl <- factor(mtcars$cyl)

The Logic of Hypothesis Testing Link to heading

State null hypothesis (H₀) and alternative hypothesis (H₁)
Choose a significance level (α, typically 0.05)
Compute the test statistic
Determine the p-value
Reject or fail to reject H₀

Remember: A p-value is NOT the probability that H₀ is true. It is the probability of observing data at least as extreme as yours, assuming H₀ is true.

4. Regression & Statistical Modelling in R

Thu, 12 Mar 2026 00:00:00 +0000

Statistical models let you quantify relationships between variables, make predictions, and test hypotheses about causal mechanisms. This tutorial covers the modelling workflow from simple linear regression to mixed-effects models.

Setup Link to heading

library(tidyverse)
library(broom)
data(mtcars)

Simple Linear Regression Link to heading

# Does weight predict MPG?
model1 <- lm(mpg ~ wt, data = mtcars)
summary(model1)

Interpreting the Output Link to heading

Intercept (β₀): Expected MPG when weight = 0 (extrapolation)
Slope (β₁): For each 1000 lb increase in weight, MPG changes by β₁
R²: Proportion of variance in MPG explained by weight
p-value: Probability of observing this slope if the true slope were 0

Tidy Output with `broom` Link to heading

tidy(model1) # Coefficient table
glance(model1) # Model-level statistics
augment(model1) # Observation-level statistics (fitted, residuals)

Multiple Regression Link to heading

model2 <- lm(mpg ~ wt + hp + cyl, data = mtcars)
summary(model2)

# Compare models
anova(model1, model2)
AIC(model1, model2)
BIC(model1, model2)

Multicollinearity Link to heading

library(car)

# Variance Inflation Factors
vif(model2)
# VIF > 5 suggests problematic collinearity

Model Diagnostics Link to heading

# Diagnostic plots
par(mfrow = c(2, 2))
plot(model2)

What to look for: Link to heading

Residuals vs Fitted: Should show no pattern (linearity)
Q-Q Plot: Points should follow the diagonal (normality)
Scale-Location: Horizontal band (homoscedasticity)
Residuals vs Leverage: Identify influential observations

# Formal tests
# Normality of residuals
shapiro.test(residuals(model2))

# Homoscedasticity (Breusch-Pagan)
library(lmtest)
bptest(model2)

# Autocorrelation (Durbin-Watson)
dwtest(model2)

Interaction Effects Link to heading

model3 <- lm(mpg ~ wt * factor(cyl), data = mtcars)
summary(model3)

# Visualise interaction
ggplot(mtcars, aes(x = wt, y = mpg, colour = factor(cyl))) +
 geom_point(size = 3) +
 geom_smooth(method = "lm", se = TRUE) +
 labs(title = "Weight × Cylinders Interaction",
 colour = "Cylinders") +
 theme_minimal()

Polynomial Regression Link to heading

model_poly <- lm(mpg ~ poly(wt, 2), data = mtcars)
summary(model_poly)

ggplot(mtcars, aes(x = wt, y = mpg)) +
 geom_point() +
 geom_smooth(method = "lm", formula = y ~ poly(x, 2), colour = "red") +
 labs(title = "Quadratic Fit: Weight vs MPG") +
 theme_minimal()

Generalised Linear Models (GLM) Link to heading

Logistic Regression Link to heading

# Predict transmission type (0 = automatic, 1 = manual)
model_logit <- glm(am ~ wt + hp, data = mtcars, family = binomial)
summary(model_logit)

# Odds ratios
exp(coef(model_logit))
exp(confint(model_logit))

Poisson Regression Link to heading

# Count data example
model_pois <- glm(carb ~ wt + hp, data = mtcars, family = poisson)
summary(model_pois)

# Check for overdispersion
deviance(model_pois) / df.residual(model_pois)
# Values >> 1 indicate overdispersion

Mixed-Effects Models Link to heading

When data has a hierarchical or grouped structure (e.g., students within schools, measurements within subjects):

Welcome to My Blog

Sun, 15 Mar 2026 00:00:00 +0000

Welcome! This blog accompanies my R Statistics Tutorial Series and covers topics like:

Tips and tricks for R programming
Statistical concepts explained intuitively
Reproducible research workflows
Updates on my research and publications

Stay tuned for more posts. In the meantime, check out the tutorial series to get started with statistics in R.

About

Wed, 01 Jan 2025 00:00:00 +0000

R. Heller Link to heading

Research with a focus on biostatistics, biomedical research, and data science. Spanning clinical research methodology, traumaimmunology, and the development of statistical tools.

Research Interests Link to heading

Traumaimmunology: Immune response after trauma, cross-species biomarker signatures
Biostatistics: Clinical trial methodology, statistical modeling, outcome prediction
Data Science: R programming, reproducible research, high-dimensional data visualization

Tools Link to heading

Contact

Wed, 01 Jan 2025 00:00:00 +0000

ORCID: 0000-0001-8006-9742

GitHub: github.com/r-heller

ResearchGate: Raban Heller

Web of Science: P-4152-2019

Publications

Wed, 01 Jan 2025 00:00:00 +0000

2026 Link to heading

A Bauer, A Arndt, L Reichenbach, N Gebauer, M Mueller, C Neumann, C Schulz, K Steinestel, R Heller, E Chteinberg, H Busch, A Riecke, A Kuenstner, H Witte. Adenosine Pathway Activation Defines Genetically Linked Immunosuppressive Subtypes in Solid Tumor Brain Metastases. Cancers. 2026, 18(7):1087.

Obada Taleb Alhalabi, Stefan Heene, Guoli Zheng, R Heller, Tim Schubert, Marcin Luzarowski, Xiaowei Zha, Johannes Walter, Lea Hansen-Palmus, Bahram Biglari, Xing-Jin Wang, Laura Ruebenacker, Thomas Skutella, Karl Kiening, Christian Patrick Schaaf, Sandro Manuel Krieg, Andreas Wilhelm Unterberg, Klaus Zweckberger, Alexander Younsi. Systemic Interleukin-4 Application Promotes Functional Recovery and Reprograms Neuroinflammatory and Molecular Responses after Spinal Cord Injury in Rats. Theranostics. 2026, 16(9):4726–4744.

2025 Link to heading

R Heller, M. Maares, T. Chillon, H. Witte, Obada T. Al-Halabi, Stefan Heene, A. Younsi, Patrick Haubruck, Lutz Schomburg, A. Moghaddam, B. Biglari, H. Haase. Total and Free Zinc Dynamics as Biomarkers for Neurological Impairment in Traumatic Spinal Cord Injury. Nutrients. 2025, 17(3).

2024 Link to heading

Chillon TS, Tuchtenhagen M, Schwarz M, Hackler J, R Heller, Kaghazian P, Moghaddam A, Schomburg L, Haase H, Kipp AP, Schwerdtle T, Maares M. Determination of copper status by five biomarkers in serum of healthy women. Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements (GMS). 2024, 84:127441.

K Estel, K Waldmann, S Roettel, R Heller, C Willy, DA Back. Traumatic Tear of the Pectoralis Major Muscle during Military Parachute Jumping. BMJ MILITARY HEALTH. 2024, 170(2):176–177.

R Heller, Marco Torri, Jasmin Gaab, Patrick Haubruck, Arash Moghaddam-Alvandi, Bahram Biglari. Descriptive Analysis of Surgical Outcomes and Stoma Formation for Treating Sacral and Anal Pressure Injuries in Spinal Cord Injury: A Retrospective Study of Selected Cases. SAGE Open Nursing. 2024, 10:23779608241229507.

MP Rayman, L Schomburg, JS Zhang, EW Taylor, G Du Laing, M Beck, DJ Hughes, R Heller. Could Selenium Supplementation Prevent COVID-19? A Comprehensive Review of Available Studies. MOLECULES. 2024, 29(11).

2023 Link to heading

Blenkinsop G, R Heller, Carter NJ, Burkett A, Ballard M, Tai N. Remote ultrasound diagnostics disrupting traditional military frontline healthcare delivery. BMJ military health. 2023, 169(5):456-458.

TS Chillon, K Demircan, J Hackler, R Heller, P Kaghazian, A Moghaddam, L Schomburg. Combined Copper and Zinc Deficiency Is Associated with Reduced SARS-CoV-2 Immunization Response to BNT162b2 Vaccination. HELIYON. 2023, 9(10):e20919.

P Haubruck, R Heller. Ongoing Refinement Remains Key in Dealing with Shifting Challenges in Traumatological Patient Care. ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH. 2023, 109(5):103653.

P Haubruck, R Heller, CL Blaker, EC Clarke, SM Smith, D Burkhardt, YLD Liu, S Stoner, S Zaki, CC Shu, CB Little. Streamlining Quantitative Joint-Wide Medial Femoro-Tibial Histopathological Scoring of Mouse Post-Traumatic Knee Osteoarthritis Models. OSTEOARTHRITIS AND CARTILAGE. 2023, 31(12):1602–1611.

2022 Link to heading

TS Chillon, M Maares, K Demircan, J Hackler, Q Sun, R Heller, J Diegmann, M Bachmann, A Moghaddam, H Haase, L Schomburg. Serum Free Zinc Is Associated With Vaccination Response to SARS-CoV-2. FRONTIERS IN IMMUNOLOGY. 2022, 13:906551.

K Demircan, TS Chillon, Q Sun, R Heller, GJ Klingenberg, IM Hirschbil-Bremer, P Seemann, J Diegmann, M Bachmann, A Moghaddam, L Schomburg. Humoral Immune Response to COVID-19 mRNA Vaccination in Relation to Selenium Status. REDOX BIOLOGY. 2022, 50:102242.

K Demircan, TS Chillon, T Bracken, I Bulgarelli, I Campi, G Du Laing, S Fafi-Kremer, L Fugazzola, AA Garcia, R Heller, DJ Hughes, L Ide, GJ Klingenberg, P Komarnicki, Z Krasinski, A Lescure, P Mallon, A Moghaddam, L Persani, M Petrovic, M Ruchala, M Solis, L Vandekerckhove, L Schomburg. Association of COVID-19 Mortality with Serum Selenium, Zinc and Copper: Six Observational Studies across Europe. FRONTIERS IN IMMUNOLOGY. 2022, 13:1022673.

M Maares, J Hackler, A Haupt, R Heller, M Bachmann, J Diegmann, A Moghaddam, L Schomburg, H Haase. Free Zinc as a Predictive Marker for COVID-19 Mortality Risk. Nutrients. 2022, 14(7).

2021 Link to heading

Seelig J, R Heller, Haubruck P, Sun Q, Georg Klingenberg J, Hackler J, Crowell HL, Daniel V, Moghaddam A, Schomburg L, Biglari B. Selenium-Binding Protein 1 (SELENBP1) as Biomarker for Adverse Clinical Outcome After Traumatic Spinal Cord Injury. Frontiers in neuroscience. 2021, 15:680240.

R Heller, Seelig J, Crowell HL, Pilz M, Haubruck P, Sun Q, Schomburg L, Daniel V, Moghaddam A, Biglari B. Predicting neurological recovery after traumatic spinal cord injury by time-resolved analysis of monocyte subsets. Brain : a journal of neurology. 2021, 144(10):3159-3174.

Gül-Klein S, Haxhiraj D, Seelig J, Kästner A, Hackler J, Sun Q, R Heller, Lachmann N, Pratschke J, Schmelzle M, Schomburg L. Serum Selenium Status as a Diagnostic Marker for the Prognosis of Liver Transplantation. Nutrients. 2021, 13(2).

B Biglari, R Heller, M Hörner, A Sperl, T Bock, B Reible, P Haubruck, PA Grützner, A Moghaddam. Novel Approach to an Early Assessment of a Patient's Potential for Neurological Remission after Acute Spinal Cord Injury: Analysis of Hemoglobin Concentration Dynamics. The journal of spinal cord medicine. 2021, 44(2):229–240.

T Bock, R Heller, P Haubruck, TF Raven, M Pilz, A Moghaddam, B Biglari. Pursuing More Aggressive Timelines in the Surgical Treatment of Traumatic Spinal Cord Injury (TSCI): A Retrospective Cohort Study with Subgroup Analysis. JOURNAL OF CLINICAL MEDICINE. 2021, 10(24).

TS Chillon, K Demircan, R Heller, IM Hirschbil-Bremer, J Diegmann, M Bachmann, A Moghaddam, L Schomburg. Relationship between Vitamin D Status and Antibody Response to COVID-19 mRNA Vaccination in Healthy Adults. BIOMEDICINES. 2021, 9(11).

J Hackler, R Heller, Q Sun, M Schwarzer, J Diegmann, M Bachmann, A Moghaddam, L Schomburg. Relation of Serum Copper Status to Survival in COVID-19. NUTRIENTS. 2021, 13(6).

MC Tanner, R Heller, A Grimm, S Zimmermann, M Pilz, L Jurytko, M Miska, L Helbig, G Schmidmaier, P Haubruck. The Influence of an Occult Infection on the Outcome of Autologous Bone Grafting During Surgical Bone Reconstruction: A Large Single-Center Case-Control Study. JOURNAL OF INFLAMMATION RESEARCH. 2021, 14:995–1005.

2020 Link to heading

R Heller, Sperl A, Seelig J, Haubruck P, Bock T, Werner T, Besseling A, Sun Q, Schomburg L, Moghaddam A, Biglari B. Zinc Concentration Dynamics Indicate Neurological Impairment Odds after Traumatic Spinal Cord Injury. Antioxidants (Basel, Switzerland). 2020, 9(5).

Doll J, Moghaddam A, Daniel V, Biglari B, R Heller, Schmidmaier G, Raven TF. LIPUS vs. reaming in non-union treatment: Cytokine expression course as a tool for evaluation and differentiation of non-union therapy. Journal of orthopaedics. 2020, 17:208-214.

M Belhadj, LSK Tani, ND Medjati, Y Harek, MD Sahi, Q Sun, R Heller, A Behar, L Charlet, L Schomburg. Se Status Prediction by Food Intake as Compared to Circulating Biomarkers in a West Algerian Population. NUTRIENTS. 2020, 12(12).

P Haubruck, R Heller, MC Tanner. Femoral Neck Fractures: Current Evidence, Controversies and Arising Challenges. ORTHOPAEDICS & TRAUMATOLOGY-SURGERY & RESEARCH. 2020, 106(4):597–600.

P Haubruck, R Heller, MC Tanner. Fractures du col du fémur : données actuelles, controverses et nouveaux défis. Revue de Chirurgie Orthopédique et Traumatologique. 2020, 106(4):335–338.

R Heller, Qian Sun, J. Hackler, J. Seelig, Linda Seibert, Asan Cherkezov, W. Minich, P. Seemann, Joachim Diegmann, Maximilian Pilz, M. Bachmann, A. Ranjbar, A. Moghaddam, L. Schomburg. Prediction of Survival Odds in COVID-19 by Zinc, Age and Selenoprotein P as Composite Biomarker. Redox biology. 2020, 38:101764.

M Karadjian, AS Senger, C Essers, S Wilkesmann, R Heller, J Fellenberg, R Simon, F Westhauser. Human Platelet Lysate Can Replace Fetal Calf Serum as a Protein Source to Promote Expansion and Osteogenic Differentiation of Human Bone-Marrow-Derived Mesenchymal Stromal Cells. CELLS. 2020, 9(4).

A Moghaddam, R Heller, Q Sun, J Seelig, A Cherkezov, L Seibert, J Hackler, P Seemann, J Diegmann, M Pilz, M Bachmann, WB Minich, L Schomburg. Selenium Deficiency Is Associated with Mortality Risk from COVID-19. Nutrients. 2020, 12(7).

J Seelig, R Heller, J Hackler, P Haubruck, A Moghaddam, B Biglari, L Schomburg. Selenium and Copper Status - Potential Signposts for Neurological Remission after Traumatic Spinal Cord Injury. Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements. 2020:126415.

T Tjardes, R Heller, D Pförringer, R Lohmann, DA Back, AG Digitalisierung DGOU. Artificial Intelligence in Orthopedics and Trauma Surgery. CHIRURG. 2020, 91(3):201–205.

H Trentzsch, G Osterhoff, R Heller, U Nienaber, M Lazarovici, DGOU, Sektion Notfall- Intensivmed Schwe, DGU. Challenges of Digitalization in Trauma Care. UNFALLCHIRURG. 2020, 123(11):843–848.

R Heller, T Bock, P Haubruck, J Seelig, A Moghaddam. Relation of Selenium Status to Neuro-Regeneration after Traumatic Spinal Cord Injury. Selenium Research for Environment and Human Health: Perspectives, Technologies and Advancements. 2020.

R Heller, J Seelig, J Hackler, P Haubruck, A Moghaddam, B Biglari, L Schomburg. Biomarkers of Selenium and Copper Status in Patients with Traumatic Spinal Cord Injury. Selenium Research for Environment and Human Health: Perspectives, Technologies and Advancements. 2020.

2019 Link to heading

R Heller, Tobias Bock, Patrick Haubruck, Julian Seelig, Arash Moghaddam. Relation of Selenium Status to Neuro-Regeneration after Traumatic Spinal Cord Injury. Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements. 2019, 51:141–149.

TF Raven, A Moghaddam, C Ermisch, F Westhauser, R Heller, T Bruckner, G Schmidmaier. Use of Masquelet Technique in Treatment of Septic and Atrophic Facture Nonunion. INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED. 2019, 50:40–54.

A Sperl, R Heller, B Biglari, P Haubruck, J Seelig, L Schomburg, T Bock, A Moghaddam. The Role of Magnesium in the Secondary Phase After Traumatic Spinal Cord Injury. A Prospective Clinical Observer Study. Antioxidants. 2019, 8(11).

2018 Link to heading

P Haubruck, A Solte, R Heller, V Daniel, M Tanner, A Moghaddam, G Schmidmaier, C Fischer. Chemokine Analysis as a Novel Diagnostic Modality in the Early Prediction of the Outcome of Non-Union Therapy: A Matched Pair Analysis. JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH. 2018, 13(1):249.

P Haubruck, J Ober, R Heller, M Miska, G Schmidmaier, MC Tanner. Complications and Risk Management in the Use of the Reaming-Irrigator-Aspirator (RIA) System: RIA Is a Safe and Reliable Method in Harvesting Autologous Bone Graft. PLOS ONE. 2018, 13(4):e0196051.

P Haubruck, R Heller, MC Tanner, V Daniel, G Schmidmaier, F Bolourchi, A Moghaddam, C Fischer. A Preliminary Study of Contrast-Enhanced Ultrasound (CEUS) and Cytokine Expression Analysis (CEA) as Early Predictors for the Outcome of Tibial Non-Union Therapy. DIAGNOSTICS. 2018, 8(3).

P Haubruck, R Heller, P Apitz, A Kammerer, A Alamouti, V Daniel, G Schmidmaier, A Moghaddam. Evaluation of Matrix Metalloproteases as Early Biomarkers for Bone Regeneration during the Applied Masquelet Therapy for Non-Unions. INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED. 2018, 49(10):1732–1738.

R Massoud, R Heller, N Moukalled, C Matar, B Haffar, A Bazarbachi, J El-Cheikh. The Efficacy and Safety of Busulfan Dose Intensity with Fludarabine Conditioning Regimen for Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation. A Single Center Experience. CLINICAL LYMPHOMA MYELOMA & LEUKEMIA. 2018, 18:S310-S311.

MC Tanner, R Heller, F Westhauser, M Miska, T Ferbert, C Fischer, S Gantz, G Schmidmaier, P Haubruck. Evaluation of the Clinical Effectiveness of Bioactive Glass (S53P4) in the Treatment of Non-Unions of the Tibia and Femur: Study Protocol of a Randomized Controlled Non-Inferiority Trial. TRIALS. 2018, 19(1):299.

F Westhauser, B Reible, M Höllig, R Heller, G Schmidmaier, A Moghaddam. Combining Advantages: Direct Correlation of Two-Dimensional Microcomputed Tomography Datasets onto Histomorphometric Slides to Quantify Three-Dimensional Bone Volume in Scaffolds. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A. 2018, 106(7):1812–1821.

2017 Link to heading

T Ferbert, C Child, V Graeser, T Swing, M Akbar, R Heller, B Biglari, A Moghaddam. Tracking Spinal Cord Injury: Differences in Cytokine Expression of IGF-1, TGF-B1, and sCD95I Can Be Measured in Blood Samples and Correspond to Neurological Remission in a 12-Week Follow-Up. JOURNAL OF NEUROTRAUMA. 2017, 34(3):607–614.

R Heller, Tim Friedrich Raven, Tyler Swing, Kevin Kunzmann, Volker Daniel, Patrick Haubruck, Michael Akbar, Paul Alfred Grützner, Gerhard Schmidmaier, Bahram Biglari, Arash Moghaddam. CCL-2 as Possible Early Marker for Remission after Traumatic Spinal Cord Injury. Spinal cord. 2017:1002-1009.

A Moghaddam, R Heller, V Daniel, T Swing, M Akbar, HJ Gerner, B Biglari. Exploratory Study to Suggest the Possibility of MMP-8 and MMP-9 Serum Levels as Early Markers for Remission after Traumatic Spinal Cord Injury. SPINAL CORD. 2017, 55(1):8–15.

2016 Link to heading

A Moghaddam, A Sperl, R Heller, HJ Gerner, B Biglari. sCD95L in Serum after Spinal Cord Injury. SPINAL CORD. 2016, 54(11):957–960.

A Moghaddam, A Sperl, R Heller, K Kunzmann, V Graeser, M Akbar, HJ Gerner, B Biglari. Elevated Serum Insulin-Like Growth Factor 1 Levels in Patients with Neurological Remission after Traumatic Spinal Cord Injury. PLOS ONE. 2016, 11(7):e0159764.

R Heller, V Daniel, T Swing, M Akbar, HJ Gerner, B Biglari, A Moghaddam-Alvandi. P29 MMP-8 and MMP-9 Serum Levels as Possible Early Markers for Remission after Traumatic Spinal Cord Injury. Injury. 2016, 47(Suppl 5):S35.

Software

Wed, 01 Jan 2025 00:00:00 +0000

R Packages Link to heading

phenoscapR Link to heading

Akoya/CODEX single-cell staining analysis and visualization toolkit for spatial phenotyping data.

GitHub · Documentation

songR Link to heading

Native R implementation of SONG dimensionality reduction for single-cell and high-dimensional data.

GitHub · Documentation

hexmakR Link to heading

Interactive hex sticker generator for R packages with Shiny interface and programmatic API.

Impressum

Mon, 01 Jan 0001 00:00:00 +0000

Angaben gemäß § 5 TMG Link to heading

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Kontakt Link to heading

Telefon: [Ihre Telefonnummer]
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Privacy Policy (Datenschutzerklärung)

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1. Datenschutz auf einen Blick Link to heading

Allgemeine Hinweise Link to heading

Die folgenden Hinweise geben einen einfachen Überblick darüber, was mit Ihren personenbezogenen Daten passiert, wenn Sie diese Website besuchen. Personenbezogene Daten sind alle Daten, mit denen Sie persönlich identifiziert werden können.

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Diese Website wird bei einem externen Dienstleister gehostet (Hoster). Die personenbezogenen Daten, die auf dieser Website erfasst werden, werden auf den Servern des Hosters gespeichert. Hierbei kann es sich v.a. um IP-Adressen, Kontaktanfragen, Meta- und Kommunikationsdaten, Vertragsdaten, Kontaktdaten, Namen, Websitezugriffe und sonstige Daten, die über eine Website generiert werden, handeln.

R. Heller

1. Descriptive Statistics in R

Setup Link to heading

Measures of Central Tendency Link to heading

Mean, Median, Mode Link to heading

When to use which? Link to heading

Measures of Dispersion Link to heading

Summary Statistics at a Glance Link to heading

Frequency Tables Link to heading

Group-wise Summaries Link to heading

Checking Normality Link to heading

Skewness and Kurtosis Link to heading

2. Data Visualisation with ggplot2

Setup Link to heading

The Grammar of Graphics Link to heading

Histogram and Density Plots Link to heading

Boxplots Link to heading

Violin Plots Link to heading

Scatterplots Link to heading

Bar Charts Link to heading

Faceted Plots Link to heading

Correlation Heatmap Link to heading

Customising Themes Link to heading

Saving Plots Link to heading

Key Takeaways Link to heading

3. Inferential Statistics in R

Setup Link to heading

The Logic of Hypothesis Testing Link to heading

4. Regression & Statistical Modelling in R

Setup Link to heading

Simple Linear Regression Link to heading

Interpreting the Output Link to heading

Tidy Output with broom Link to heading

Multiple Regression Link to heading

Multicollinearity Link to heading

Model Diagnostics Link to heading

What to look for: Link to heading

Interaction Effects Link to heading

Polynomial Regression Link to heading

Generalised Linear Models (GLM) Link to heading

Logistic Regression Link to heading

Poisson Regression Link to heading

Mixed-Effects Models Link to heading

Welcome to My Blog

About

R. Heller Link to heading

Research Interests Link to heading

Tools Link to heading

Contact

Publications

2026 Link to heading

2025 Link to heading

2024 Link to heading

2023 Link to heading

2022 Link to heading

2021 Link to heading

2020 Link to heading

2019 Link to heading

2018 Link to heading

2017 Link to heading

2016 Link to heading

Software

R Packages Link to heading

phenoscapR Link to heading

songR Link to heading

hexmakR Link to heading

Impressum

Angaben gemäß § 5 TMG Link to heading

Kontakt Link to heading

Verantwortlich für den Inhalt nach § 55 Abs. 2 RStV Link to heading

Haftungsausschluss (Disclaimer) Link to heading

Haftung für Inhalte Link to heading

Privacy Policy (Datenschutzerklärung)

1. Datenschutz auf einen Blick Link to heading

Allgemeine Hinweise Link to heading

2. Hosting Link to heading

Tidy Output with `broom` Link to heading