# A primer for biostatistics in R

# Chapter 1 Introduction

Welcome to a primer for biostatistics in R.

Mathematical! Adventure time! Well, the mathematical part is up to you, but this is an adventure. This set of learning materials is a guide developed to support you in better developing critical thinking using statistics. Critical thinking very generally is a mode of thinking that is self-directed and evidence based (Facionie 2017). Statistical thinking is thus an ideal opportunity and partner in honing literacy adventure skills in this domain. Enhancing clarity, accuracy, precision, relevance, depth, breadth, significance, logic and fairness - all key criteria of critical thinking - with data or evidence both quantitative and qualitative is a profound tool as a scientist and citizen. It should be fundamental to statistics. Hence, the primary goal of this set of materials is to engender statistical thinking that embodies these principles and explores these criteria using data.

The open and free resources associated with learning statistics is nearly infinite online particularly in R. The programming language R is a free, open source programming environment ideal for statistics. There are other similar alternatives, but here R is used to support and scaffold critical thinking and statistical literacy because a significant component of many biologists use R including ecologists (Lai et al. 2019). Importantly, it provides a simple and clear mechanism to document, annotate, tidy up, write down, and literally show your work - like in math class. This benefits you. You see your ideas written down and can explore logic, fairness, and all the criteria listed above. It also enables you to repeat, replicate, and share your work.

### Course outline

If you are electing to engage with this learning opportunity formally for BIOL5081 at York University, here is the official course outline.

### Learning outcomes

- Build a tidy, logical data model for a graduate-level dataset.

- Develop a reproducible data and statistical workflow.

- Design and complete intermediate-level data visualizations appropriate for a graduate-level tidy dataset.

- Identify a range of suitable univariate or multivariate statistical approaches that can be applied to any dataset.

- Interpret statistical output to quantify statistical model performance.

- Complete fundamental exploratory data analysis on a representative dataset.

- Appreciate the strengths and limitations of open science, data science, and evidence-based collaboration models.

### Structure

Read a book. The new statistics with R. (Hector 2021).

Write a book review. Ten simple rules for writing statistical book reviews (Christopher J. Lortie 2019) suggests a critical thinking framework to adopt for this process.

Learn-by-doing here.

Do a hackathon.

Do a hackathon as a test and submit for grading & review.

#### Rationale

Some learn best by reading. Some learn best by doing. We can all benefit from both approaches to refining our critical thinking through statistics.

Two summative (i.e. graded outcomes) include the book review and the test.

### Schedule

Slide decks are optional. The decks simply highlight some of the connections between the criteria for critical thinking and statistical heuristics.

week | adventure | slide deck |
---|---|---|

1 | Tidy data in R and CH9 in textbook | whyR |

2 | Literate statistical coding and Data science and CH11 in texbook | wrangleR |

3 | Statistics for ecology and evolution I and CH7 in textbook | contemporary viz |

4 | Statistics for ecology and evolution II and CH15 in textbook | EDAR |

5 | Book review due and hackathon | efficient stats |

6 | Test | when to publish data & code |

### Instructions

Read the text at your own pace. At least hit the key chapters CH4, 10 & 11 to write the review and submit your insights by the fifth week of work (if you choose to do 1-2 tasks per week as suggested in the schedule). If you are taking BIOL5081, please see official course outline and submit all work to turnitin.com as PDF only (even for the R work - knit to pdf).

Each week, read, discuss if you elect to work synchronously, and try the challenge provided.

The final two weeks, that hackathon is a warm up to the test. Grab the dataset, apply your critical thinking skills, code and show your work, and capture code and outputs as PDF. The hackathon is a stepping stone, formative process for to check if you are ready to think on your feet, write code, and apply biostatistical thinking to a challenge. The test is the exact same approach but summative, i.e. you submit for review and grading to a peer or instructor like me.

### Citation

Lortie, CJ (2021): A primer for biostatistics in R. figshare. Book. https://doi.org/10.6084/m9.figshare.15048597.v2

### License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

### Tidy data in R

Tidiness is next to naturalness. We are wired up to see patterns and organize. Put that tendency to good work in data and statistical critical thinking.

#### Learning outcomes

- Consider data structures such as long versus wide.

- Read in a dataset to the R environment.

- Do a t-test.

#### Critical thinking

Tidy data thinking was pioneered in the R world (Wickham 2014). This philosophy to first considering the basic format of your data is transformational and profound. It beautifully connects to logic. Better yet, it sets you up for easier stats and plots in many environments including R. There is an excellent chapter on this topic in the free, open text R for Data Science.

#### Adventure time

Very simple life data to explore some ideas about meditation, steps, resting heart rate and the importance of instrument variation. Data are here. Explore the t-test in R for this adventure. Is the number of steps or sleep different from 0? Do the means estimated from a watch versus simple Fitbit tracker vary for simple measures? Did 0 versus 12 mins of meditation per day influence a relevant measure?

Deeper dive: explore the var.equal or alternative argument. Test nonparametric analog to this test.

```
library(tidyverse)
<- read_csv(url("https://ndownloader.figshare.com/files/28920855"))
simple_life simple_life
```

```
## # A tibble: 9 × 7
## simple_date steps_fitbit sleep_fitbit hr steps_watch sleep_watch
## <date> <dbl> <dbl> <dbl> <dbl> <dbl>
## 1 2021-06-02 20913 429 54 25197 314
## 2 2021-06-03 6904 447 53 13042 302
## 3 2021-06-04 19548 449 56 23285 413
## 4 2021-06-05 19311 423 56 25832 355
## 5 2021-06-06 26159 435 58 29533 385
## 6 2021-06-07 21618 358 56 27796 240
## 7 2021-06-08 20890 492 53 24360 434
## 8 2021-06-09 12008 541 53 14517 399
## 9 2021-06-10 18058 436 57 22392 403
## # … with 1 more variable: meditation_mins <dbl>
```

#### Reflection questions

- What can a t-test do? Can you imagine other functions for a t-test in the context of your work and life?
- What are the limitations of a t-test?
- Is the data structure wide, long, and how can you consider tidying this evidence? Are there variables that represent the same concept?