DEV Community: Mutuku joseph

How Analysts Translate Messy Data, DAX, and Dashboards into Action Using Power BI...

Mutuku joseph — Sat, 07 Feb 2026 12:10:15 +0000

Part 1

Introduction to Power Bi.

Power BI is a data analysis and visualization tool by Microsoft that helps turn raw data into charts, graphs, and reports.
In this beginner friendly guide,I will take you through all the essentials to get you started on your data journey. We will cover how to import data, build your first charts and even how to share with others.
However , we will first have to download and install power Bi on our laptops/desktops.

1.Importing Data

On the home screen, choose blank report. this is the first step to data importation.
This should be your screen after blank report,

This is the report view, at the center of it are some of the most common data sources.
Power bi lets you get data from so many data sources, excell, dataflows, dataverse, and even sql servers,cloud services etc.
By clicking the top first icon, you can see the various data sources;

Data sources in power bi

However for this guide we will use data from an excell workbook. So on the menu, click of excel workbook and choose the data from your files.
*Nb * A common first time problem-sometimes data is saved as with a .csv extension thus the file might not be visible with the excell files, on your files list click all files to be able to view the csv file.

2.Load and Transform data

Once you have your data, the first step is to load the data to powe bi.Mostly this data is messy and not standardized to the right data types for analysis, has missing values or duplicates.

Below you will see; load and transform data icons.

Load data- if you load data, powe bi will bring in the data exactly as it appears in the excell file, straight import. No data cleaning will have been made
Transform data- we click on transform, you will open what we call the power query. This is an editor for data,its used for data cleaning even before loading it.

NB You can always prepare and transform data after loading, use the transform data icon to get to power query mode.

3.Data cleaning in power bi

Data cleaning in Power bi is done using the power query, and is the process of preparing data so it is accurate, complete, and ready for analysis. It involves fixing errors, removing duplicate or unwanted data, and organizing information into a clear format.

some common data cleaning actions:

remove extra columns
clear or correct blanks
Check fro duplicates
_ Fix wrong values_
Standardize data types in columns
column split

However, the action is not really deleting, the queries are stored on the right side under applied steps and an action can always be undone incase it was a mistake.

Once you are done click on close and apply on the top left to apply the changes you have made to the table.

4.Table view and report view

Table view is where our our actual data is ,and where data manipulation happens, once that is done the actions/results can be seen in the report view as charts,table or card visuals.

5.Data models

For data analysis, the analyst has to define the appropriate relationship model for the data.
A relation is a definition of how tables in the data set are related and communicate to each other.We have a Facts table and several table stemming from the central table, called dimension tables.

6.DAX and Logical Functions

DAX function create the bussiness logic and are the queries that help the analyst draw insights from the data.
That way the analyst can answer the questions that are arising from the data set basing the reasons on actual data.

7.Dashboard and reports

The analyst then draws and compares trend logically to come up with a detailed report.
The analyst then prepares a one page dashboard that highlights the key KPIs from the data in the form of charts,cards and tables.

The analyst then shares the findings with the relevant stakeholders for action.

A begginers guide into the world of data visualization with power Bi.

Mutuku joseph — Thu, 05 Feb 2026 10:05:02 +0000

Part 1 Introduction to Power Bi.

1. Download and and install power Bi

To get started we will download and install power bi desktop, it is free and gives you all you need to build a project from scratch
on your computer search bar, type in Microsoft store. This resource comes already pre installed so you will definitely find it.
Once there search for a Power Bi desktop.
This is the icon:

Once downloaded,go to download and launch to install.
Once its installed you will see this home screen

Now we can import data, build dashboards and even reports

2.Importing Data

On the home screen, choose blank report. this is the first step to data importation.
This should be your screen after blank report,

Data sources in power bi

However for this guide we will use data from an excell workbook. So on the menu, click of excell work book and choose the data from your files.
*Nb * A common first time problem-sometimes data is saved as with a .csv extension thus the file might not be visible with the excell files, on your files list click all files to be able to view the csv file.

3.Load and Transform data

Once you have your data, below you will see load and transform data icons.

NB You can always prepare and transform data after loading, use the transform data icon to get to power query mode.

4.Data cleaning in power bi

some common data cleaning actions:

remove extra columns
clear or correct blanks
Check fro duplicates
_ Fix wrong values_
Standardize data types in columns
column split

However, the action is not really deleting, the queries are stored on the right side under applied steps and an action can always be undone incase it was a mistake.

Once you are done click on close and apply on the top left to apply the changes you have made to the table.

5.Table view and report view

Table view is where our our actual data is ,and where data manipulation happens, once that is done the actions/results can be seen in the report view as charts,table or card visuals.

Schemas and data modelling in Power Bi, a begginers guide.

Mutuku joseph — Sun, 01 Feb 2026 19:53:39 +0000

Introduction to Power Bi.

Power BI is a data analysis and visualization tool by Microsoft that helps turn raw data into charts, graphs, and reports.
In this beginner friendly guild line I will take you through all the essentials to get you started on your data journey.

In this article I will take you through schemas and data modelling in Power BI, focusing on concepts such as star schema, snowflake schema, relationships, fact and dimension tables, and why good modelling is critical for performance and accurate reporting.

Schemas and Data modelling in Power bi

Data modelling -this the action of setting up data tables, relationships, calculations and scenario building.
So technically, a date model is semantic layer for power Bi reports.

Key definitions to note early on;
Relationship- this defines all tables and how they relate with each other
physical model- is actually a representation of how data is stored in the database
logical model is a representaion of how bussiness interpret this stored data

Fact table-stores numerical data used for analysis
Dimesnion table- stores descriptive information, normally reffering to data in the facts table.

Schemas
In very simple terms, a schema is the organization of data. A representation of how the database is setup
We will the look at types of schemas, namely Star schema and snowflake schema.

Star schema
Is a simple blueprint that consists of one or more fact tables that are referencing a number of dimension tables.

Use this visualized image to understand further, at the center is how fact table, sorrounded by a number of dimension tables

Nb That kind of arrangement gives this database structure the name,star schema

Snowflakes schema
This is an extension of the star schema. additional dimension tables are create from existing dimensions, it adds additional dimensions to represent hierarchies in the data. This reduces redundancy hence the model is more efficient.

_Fact table _
From the definition above, a fact table-stores numerical data used for analysis

Lets use a practical example of student data, how would a star schema of the database look like;

Relationships
This defines all tables and how they relate with each other. usually a fact table to dimensional tables using columns from each other
Therefore applying the relationship model we can filter multiple data values from a relationship of tables
There are 3 types of relationships

1 to 1 whereby a column has only one instance of a value and other related table has only one instance of that value.

Many to 1 - whereby, we have more than one instance of a value. and other related table has only one instance of that value

**Many to many **a connection of many-to-many relationship between the table in this relationship

Normalized model, is whereby we create more tables with fewer columns. this reduces redundancy and inconsistences
-maintains data integrity
optimizes disk space

denormalized model-
we have fewer tables and more columns and records

Snowflakes schema
Is the extension of a star schema, whereby dimension tables have dimension tables.

Good modelling is critical for performance and accurate reporting.It ensures accuracy in analysis.
A well structured model even in growing data environment reduces loading time, reduces incorrect results and creates trustworthy interactive reports.

Enjoy your modelling journey

Data Analysis with Microsoft Excell, a begginers guide!

Mutuku joseph — Sun, 25 Jan 2026 20:32:07 +0000

Introduction to excel fundamentals...

Excel is often the first and most important tool in any analyst’s toolkit. This beginner-friendly guide walks you through Excel step by step, starting with the basics and building toward practical use cases, cleaning data, running calculations, and uncovering patterns.

1.Basic installation and first time using.

In this chapter, we will look at the basics on installing excell on our local computer, feel comfortable opening and using Excel

Use this link to download and install;[(https://www.microsoft.com/en-us/download/office.aspx)]

However, most windows operating systems come with the excel pre installed as part of microsoft office.
Use the installed excell and learn basic the excel interface:
Key words to note;
Workbook and worksheet
Workbook- is in the simplest term the collection of excell data sheets
Worksheet- is a template containing rows and columns where you enter data.
-Rows- Rows run horizontally (left to right). Contains a complete record
-Columns- Columns run vertically (top to bottom).
-Cells-cell is where a row and a column meet, where data is entered, one piece of information
So by the end of this first lesson, we all should be able to download, install and open excell
Enter sample data in an excell worksheet and save the sheet.

2.Core basics and exercises

In this stage, we will learn to for perform simple tasks.
Cell formatting (Including data types)
In excell, we have several data types that are recoqnized during data manipulation
Namely: Numbers, Integers, currency, dates, decimal, etc
Excell allows several data analysis options and arithmetic calculation,it allows, addition, subtraction,division, calculating means, averages, standard deviation among others.

By the end of this exercise , we need to be able to use basic formulas confidently to manipulate the excell data we just entered

3. Data cleaning and logical functions

Next comes learning the core fundamentals, this will include formatting cells, sorting and filtering data, and using basic formulas like addition, subtraction, averages, and percentages.

Therefore we will work with real datasets, not just small tables.
Data cleaning is the foundation of accurate data analysis. Data must be cleaned — because even the best analysis will fail if the data is incomplete or incorrect.
Common data problems; Missing or blank values, Duplicate records, Inconsistent formatting (dates, text, numbers).

Data validation- Is the process that ensures the cleaning process didn’t introduce new mistakes. During data entry , one can set a primary key to ensure standardization to avoid duplication..

However incase of a duplicate, excel has a remove duplicate function that allows you to find and remove duplicate
Conditional formatting,- is a data cleaning method that changes the color of the selected cells based on the rules you define.

4. Analysis and Visualization

Excell allows you to transform messy data into visuals that are easy to understand and draw conclusions to make business decisions. There are several tools for this task:
• Bar and column charts for comparisons and pivot charts
• Line charts for trends over time-data involving dates
• Pie charts for proportions
• Simple KPIs (growth, share, averages)

4.Practical use and visualization

• Dashboards
• KPIs

In conclusion,mastering data analytics in Excel equips beginners with a practical skill that applies across industries and careers Lets goo!

A Beginner’s Guide to Using Git Bash and GitHub

Mutuku joseph — Sun, 18 Jan 2026 07:18:00 +0000

Hey! So you want to get into tech—but you’re not sure where to start. You’ve heard terms like code, databases and they all sound important… and confusing. Don’t worry. This guide is built for beginners on github and git bash, focusing on clarity over complexity and progress over perfection. Lets dive in.

Basic definitions

Git Bash
Is a command line based module that developers use to manipulate projects on github. Through version control developers can work on several segments of the same project simultaneously without interrupting each other.
GitHub
Is a cloud based service where developers host projects and work on them collaboratively over the internet.
It allows allows developers to:
-store, manage and share projects
-collaborate on projects with others
-track changes made to files

Setting Up GitHub

Before using Git Bash, you need a GitHub account:

To get started on github, you need to
.go your browser of choice
.go the github website and sign up with your username and email to creat an account.
Use this link to create a github account; [https://github.com/]

Setting Up Git Bash

Next, let’s set up Git Bash on your computer which is our local host/repository:

To get started on git bash terminal;
. you go to the git bash website,
.download and install it on your computer.
Actually Git bash terminal comes included and ready for you to run git commands.
Use this link to download and install git bash;[https://git-scm.com/]

Git Bash lets you run Git commands and basic Linux commands right from your computer. Once installed, you’re ready to start managing projects.

Getting Started with Git Bash

Step 1: Check Git Version

Open Git Bash and type out:
git --version
This checks the just downloaded version of your git bash
This also confirms Git is installed.

# this is how you check the version
$ git --version
#or
git version

Step 2: Configure Your Name and Email

Git needs to know who you are so it can track changes:

#This is how you setup your name on git
$git config --global user.name "Your Name"

#use this to setup your email on git
$git config --global user.email "your email"

To check if the configuration worked use;
git config--global--list

$git config --global --list

SSH key

Then go ahead and create a ssh key- an ssh key is a secure way to interact with git bash and github without needing a password everytime.

# this is how you generate an ssh-key
$.ssh-keygen -t ed25519 -C "email"

# then check whether key was generated
$ ls ~/.ssh 

# the turn the key into the SSH agent
$eveal "$(ssh-h-agent/-s)"

#then add the ssh key agent to git bash
$ssh-add~/.ssh/id_ed25519

Creating Your First Local Repository

Think of a repository as a folder holds and tracks all your project changes.

Create a folder for your project:
mkdir folder1
Move into the folder:
cd folder1

# This is how you creat your repo in git
$mkdir folder1

#the change directory to that folder
$cd folder1
$git init

Now this folder is your local repository, where you’ll work on files and save changes.

Creating a Remote Repository on GitHub

You also want a version online, so your work is backed up and shareable:

Log into GitHub and go to Repositories.
Click New repository, give it a name, and add a short description.

Later, you’ll connect this online repository to your local one so you can sync your work.

Initializing Git in Your Local Repository

Tell Git to start tracking your project:

git init

Create your first file:
touch "file name"

#once you cd to the current folder,you initialize 
$git init

$create a file 
$touch file1

created files that are then saved on the main folder for easy access and are eventually pushed to github

Saving Changes with Commits

A commit is like hitting “save” in a video game—it creates a checkpoint, and you can always go back to that point.
This is because;
-git keeps track of all files changed and by whom
-git keeps track of times the change was made and has a message of the nature or reason for the change

Step 1: Stage Your Changes

$git add "file name"   

# used to add several files
$git add .

Step 2: Commit Your Changes;

git commit -m "commit message"

git commit -m "commit message"

Connecting Local and Remote Repositories

Link your local repository to GitHub:
we then have to connect out remote repository (github repo) to our locally hosted repository. This ensure that changes commited locally reflect on our github.

git remote add origin "YOUR_REMOTE_REPO_URL"

Push your changes online:
The final stage is then to push the changes made from our local repository to our remote repository on github.

git push -f origin main

Once you have created files and worked on them,its time to staging area

$git add "file name"
# or use for several files
$git add .
# commit the changes(move staging files to local repo)
$git commit -m "add commit message"

Then add the changes to the local repo ready to push to guthub

$git remote add origin "github repo url"

push the changes to the remore repo

$git push -f origin main/master

$git remote add origin "github repo url"

$git push  -f origin main/master

You can also do this using VS Code’s Source Control panel if you prefer a visual interface.

Pulling Changes from GitHub

When someone else makes changes—or when you switch computers—you’ll want the latest version of the project. This is called pulling:

git pull

To pull in this context is downloading a project file with the current chnages to your local host and working on them.
This command connects to the remote repository (github repo) to download and updates the local files

git pull

Understanding Version Control

Version control is what makes Git powerful. It:

Tracks every change made to your files
Lets multiple people work on the same project safely
Helps you undo mistakes
Keeps a complete history of your project

Branching

A branch is a separate version of your project. You can experiment or add features without touching the main project. Once it’s ready, you merge it back.

git branch new-feature git checkout new-feature git merge new-feature

Tracking Changes

Git tracks changes in three steps:

Local repository/working area – where you edit files
Staging Area – where you prepare changes for saving (git add)
Repository – where changes are permanently saved (git commit)

To check what’s changed use:

# to check changed files
$git status

# to check what was actually changed
$git diff

Simple Visualization Git Workflow

Look at you now! All ready to kick it on git bash and git hub.

Post over there regulary and share widely for practice as always makes perfect. Lets go!