# Articles by Yossi Levy

### Creating MS Word reports using the officer package

February 17, 2020 |

Commonly, the final product that a data scientist or a statistician generates is a report, usually in MS Word format. The officer package enables generating such a report from within R. It also enables generating PowerPoint presentations, but this is… Continue reading →

### Visualization of the Debt/GDP ratio and national debt level

February 5, 2020 |

I saw this graph on Twitter a few days ago: [1] Short googling revealed that this is a relatively old graph from October 2017. On one hand, this is a really cool visualization. On the other hand, it also belongs… Continue reading →

### How to select a seed for simulation or randomization

March 14, 2019 |

If you need to generate a randomization list for a clinical trial, do some simulations or perhaps perform a huge bootstrap analysis, you need a way to draw random numbers. Putting many pieces of paper in a hat and drawing them is possible in theory, but you will probably be ... [Read more...]

### Pi day quiz

March 14, 2019 |

Today is the Pi Day – an annual celebration of the mathematical constant Pi. It is observed every year on March 14, since Pi can be approximated by 3.14, and the this date is written as 3/14 in the month/day format. To celebrate this day, here is a short quiz about Pi. You ...

### Cancer clusters and the Poisson distributions

March 5, 2019 |

On March 1, 2019, an article was published in Israel’s Ynetnews website, under the title “The curious case of the concentration of cancer”. The story reports on a concentration of cancer cases in the town of Rosh Ha’ayin in central Israel. In the past few years dozens of cases of ...

### The delta method and its implementation in R

March 1, 2019 |

Suppose that you have a sample of a variable of interest, e.g. the heights of men in certain population, and for some obscured reason you are interest not in the mean height μ but in its square μ². How would you inference on μ², e.g. test a hypothesis or calculate a ... [Read more...]

### Powerball demystified

March 1, 2019 |

The US Powerball lottery hysteria took another step when no one won the big jackpot in the last draw that took place on October 20, 2018. So, the total jackpot is now 2.22 billion dollars. I am sure that you want to win this jackpot. I myself want to win it. Actually, there ... [Read more...]

### A brief history of clinical trials

March 1, 2019 |

The earliest report of a clinical trial is probably provided in the Book of Daniel. Daniel and a group of other Jewish people who stayed at the palace of the king of Babylon, did not want to eat the king’s non-Kosher food and preferred a vegetarian diet. To show ... [Read more...]

### What is logistic in the logistic regression?

March 1, 2019 |

Suppose that you are interviewed for a data scientist role. You are asked about logistic regression, and you answer all sorts of questions: How to run it in Python, how would you perform feature selection, and how would you use it for prediction. For the last question you answer that ...

### Some comments on AB testing implementation

March 1, 2019 |

Many job postings in the field of technology (mainly for Data Scientist jobs, but not only) require knowledge and/or experience in “AB testing”. What is AB testing? A brief inspection at Wikipedia reveals that this is a method for assessing the impact of a certain change when it is ... [Read more...]

### How to make children eat more vegetables

February 28, 2019 |

Will plates with vegetables and fruit paintings cause children to eat more vegetables and fruits? Here is an example for how not to test this hypothesis [Read more...]