## ◾ Analyzing a Data Column

Learning goal: You can calculate the average and standard deviation from numbers in a text le. 3.1 IN THIS CHAPTER YOU WILL LEARN

• How to read numbers from a table

• How to read and write les

• How to calculate average values

• How to calculate a standard deviation

3.2.1 Problem Description

Neurobiological research studies, among other things, what conditions make neurons grow. e growth of neuron cells can be analyzed by uorescent microscopy. You obtain images in which you can measure the dendritic arbor complexity. Soware like Image J (Image Processing and Analysis in Java, http://rsb.info.nih.gov/ij/) makes it possible to calculate parameters like the dendritic length and to write the values to a text le. Simplied, the le neuron_data.txt is a text le containing the length of neurons in a single column of data:

If you need to work with such a set of numbers in a text le, there are several questions right at the beginning: How many measurements are there? What is the longest dendritic length? What is the shortest? What is the average length? What is the standard deviation? It would be great to see a quick summary before analyzing the data in more detail.