Forem: Marion Mukomi

How Analysts translate messy Data, DAX & Dashboards into Action using POWER BI

Marion Mukomi — Mon, 09 Feb 2026 13:23:05 +0000

Power BI has over 200 formulas that can be used for data analysis and visualization. Today, I'll be talking about the two different ways you can analyze and translate data in Power BI.

Before loading data into Power BI, please ensure your data is cleaned.

How to clean data
Before loading your data into Power BI, always ensure that it's cleaned for easier calculations and visualization.
We use Power Query to clean data in Power BI.
Open Power BI>open blank page> get data>click transform data to open Power Query.

Steps to follow

Remove duplicates
Remove errors
Apply text, number, and date filters like unknown for specific conditions.
Rename columns clearly.
important Change the data types. Format the different types of data into the correct type of data according to Power BI.

Data types- Whole Number–Integers (e.g., 10, 25)
- Decimal Numbers.
- Fixed Decimal Number(Precise financial values).
- Text(Words or strings).
- Date/Time(Dates and timestamps).
- True/False.

Replace/remove blanks to prevent more errors. Ensure you check the resulting table in the data view to spot issues you might have missed and save your work
Click close & apply to load your data into Power BI.

Power BI visuals

A calculated column is a new column that calculates a value for each row and stores it in Power BI, just like a formula column in Excel. These columns can be used to filter and slice data with precision. They are used directly in slicers, filters, and visuals where you need fixed, stored values.
A measure is a formula that Power BI calculates on the fly based on the current filters or visuals, without storing data.

DAX- Data Analysis Expressions. These are formulas inside Power BI.

Essential DAX formulas

Aggregate functions SUM - adds all numeric values in a column.

SUMX - adds up values row by row after applying a calculation to each row.

AVERAGE - finds the average of a column.

COUNT
Counts numeric values in a column
COUNTROWS -counts the number of rows.

COUNTX - checks each row, then counts the non-blank results.

Filter functions

CALCULATE - changes filter context for a calculation.

Note - This measure calculates total revenue for Maize by filtering the Crop Type to Maize.

FILTER - returns a table that will keep conditions if true, and omit if false.

Note - This measure calculates total profit for crops with a yield above 3000 kg.

ALL - removes filters from a column or the whole table.

Note - this measure ignores all the slicers and filters.

IF - do this or that
You can check my detailed article on the if functions and their uses. uses of if function in data analysis

SWITCH - lets you check several conditions in one expression. If the first condition is true, do one thing; if the second is true, do another; and if none are true, do something else.

RANKX - gives each row a rank based on a measure, starting at 1 for the largest value.

MIN/MAX - return the lowest/highest value.

DASHBOARDS
Analysts also translate data into meaningful insights using dashboards in Power BI. Dashboards are mainly used for data visualization.
Data visualization is useful for data cleaning, exploring data structure, detecting outliers and unusual groups, identifying trends and clusters, spotting local patterns, evaluating modeling output, and presenting results.
Shown below is an example of an interactive dashboard that uses different visualizations to showcase trends and data types across a company.

Types of charts
Pie charts - used to show the relationship between parts and the whole.

Line chart - this is used for showing trends, relationships between data, and changes over time.

Bar/Column chart - they are used to show trends, differences in trends, and relative sizes.

Matrix - This is used to compare data findings across multiple rows and columns.

Map chart - used to showcase data findings by location.
Nairobi county map

Table chart - This type of chart displays detailed data.

Q&A chart - A Q&A chart lets you ask simple questions like (total profit), and Power BI gives you a visual with the answer automatically.

Power BI charts are the vibrant and informative windows through which data comes to life.
These charts are not just data visualisations, they're vital tools for gaining insights, making data-driven decisions, and telling compelling stories.
As a data analyst, this statement is what makes you, right?
Stay tuned for my next piece.😊

Schemas and data modelling in Power BI(INTRO)

Marion Mukomi — Mon, 02 Feb 2026 13:41:47 +0000

What is Data Modelling?
This is simply setting up tables, relationships, calculations, and access for analysis tasks.
Types of tables
Fact table - does not contain actual info. Contains pointers to other tables. It's really long and narrow because of the few columns.
Dimension table - each table explains one dimension of data. This is like the owner of that information. Normally shorter compared to the fact table. It has many rows.
Setting up this data is called data modelling.

Types of Database Schema

conceptual database schema - It defines entities, relationships, and constraints without getting into implementation details. The conceptual schema is useful in the early stages of database design to map business requirements to database models.
logical database schema - Focuses on what data is stored. This defines the tables, columns, relationships, and views.
physical database schema - defines how the data is stored in the actual hardware.

Star Schema
Has one central fact and many dimensions connected. A star schema is used to organize data in a database so that it is easy to understand and analyze. Star schemas can be applied to data warehouses, databases, data marts, and other tools.

Linking Star Schema to POWER BI
This implements a star schema in Power BI using a sample data file.

import data from Excel(load data from all the tables needed)
Go to the model view and link all the tables to the fact table. Drag and drop the fact table onto all the dimensional tables that don't connect automatically to link them.
You will get a pop-up asking if you want to link the two tables, their relationship, and cardinality(nature of the relationship). Confirm all details before clicking save.
Double-check the relationships by clicking on the lines that connect the dimensional tables to the fact table. You can also use a manage relationships tab for this task.
Filtering a dimension also changes data in a fact. -The arrows on a star schema enforce the filtering effect on every table.

Snowflake Schema
This is a fact of a fact relationship. In a star schema, all the tables are connected to the fact from a one side of the relationship to the many side, whereas in a snowflake schema, we can have many one side dimensions and other dimensions that are connected to the relationship from the many side.
watch the direction of the arrows in a relationship to identify a snowflake schema
Step-by-step explanation for navigating and editing a snowflake schema

Snowflake schema sample
Important - watch the directions of the arrows from the fact table in the relationship.

EXCEL MASTERY: Beginner's complete guide.

Marion Mukomi — Sun, 25 Jan 2026 09:08:42 +0000

INTRO
Excel is extremely important in data analysis. Most analysts use Excel daily. It’s a tool used to clean data, perform calculations, analyze trends, and create reports.
Listed below are the step-by-step guidelines to help you move from beginner to mastery.

1. Interface and Piloting
An Excel workbook has cells (the rectangular boxes), columns (across the top with different letters), rows (on the left with numbers going down the screen), the ribbon (the green command center at the top of the window), and the Quick Tool Access Bar.
Cell addressing- Every cell has a name based on its column and row.
Example: Cell D3 is the intersection of Column D and Row 3.

2. Data entry, Formatting, and Validation
Excel treats texts, numbers, and dates differently. It sees this (31/12/2025)as a number and (New Year's Eve) as a text.
Data entry in Excel
Number formatting helps make data clear and precise. Some of the number formats include:

General – default format
Number – controls decimal places (quantity, scores, measurements).
Currency – shows money values (accounting).
Percentage – converts values to % (ratios and rates).
Date/Time – displays dates correctly (calendar dates).
Comma style – adds thousand separators

Conditional Formatting
This helps you spot issues and trends easily by changing the appearance of cells based on the rules you set. Types of conditional formatting include:

Highlight cell rules -greater than, less than, between, equal to, text that contains, duplicate values.
Color Scales -creates value ranges like a heatmap effect.
Icon sets -adds small symbols next to your data.
Data bars -turn your cells into mini-bar charts.
Top/Bottom rules -compares a cell's value to the other data in the selected range.

Important Formulas for Data Analysis
A formula is an instruction for Excel to calculate something. An Excel formula must always start with =. These formulas are essential in manipulation, cleaning, and interpreting data.
a. Aggregate Functions
These are the basic functions, and they summarize multiple values into a single result.

SUM – adds values
AVERAGE – calculates the mean
COUNT – counts numeric values
COUNTA – counts non-empty cells
MAX – returns the highest value
MIN – returns the lowest value

Conditional Aggregate Functions

SUMIF / SUMIFS – adds values that meet one or more conditions.
COUNTIF / COUNTIFS – counts values that meet one or more conditions.
AVERAGEIF / AVERAGEIFS – averages values that meet one or more conditions.

b.Text Functions
These functions clean, format, and manipulate text data. (They prepare data for look-up). IDs, addresses, and coordinates should always be forwarded to text.

TRIM – removes extra spaces
LEFT – extracts text from the left
RIGHT – extracts text from the right
MID – extracts text from the middle
LEN – counts characters in text
UPPER – converts text to uppercase
LOWER – converts text to lowercase
PROPER – capitalizes the first letter of each word
CONCAT (CONCATENATE) – joins text together
TEXT – formats numbers as text

c.Logical Functions
These functions perform logical tests and return one value for True/false.

IF
The IF function is used to flag conditions and categorize values supporting logical analysis.

A nested IF function in Excel chains multiple IF statements together within a single formula to evaluate several conditions, allowing for more than two possible results.

AND/OR
These two are used to test multiple conditions at once. They create more accurate decision logic in analysis.

d.LookUp Functions
These are like the search engine in your spreadsheet.

VlookUp(Vertical LookUp) It's used to search for a value in the first column of a table and return a related value from another column.
HlookUp(Horizontal LookUp) It's used to search the first row of a table for a value and return a related value from the row below.
INDEX+MATCH INDEX and MATCH are used together to perform powerful and flexible lookups in Excel. PIVOT TABLES Pivot tables summarize and analyze large data sets quickly. They reorganize raw data to show totals, averages, counts, and comparisons without complex formulas.

SLICERS
Slicers in Excel are interactive, visual buttons that filter data in tables, PivotTables, and PivotCharts, offering a more user-friendly way to drill down into data than traditional filters, making them ideal for dashboards and quick data exploration.

How to insert a slicer

Click anywhere inside your Pivot Table.
Go to the PivotTable Analyze tab on the Ribbon.
Click Insert Slicer.
A window will pop up with all your data headers. Check the box for the field you want to filter by (e.g., "Region" or "Salesperson") and click OK.

CHARTS
Charts help to show trends, patterns, comparison and relationships in data at a glance. They help improve dashboards by making insights clear and visual.
Chart types - column/bar, pie, line, and area.
Example
Below is a chat created to track the performance score of employees over 12 months.

*Chart Insights *

There is a consistently high performance with an overall average score of about 4.96.
Performance peaks in the first quarter(March).
Performance peaks in the last quarter(October).
There is a performance drop in July, showing a mid-year slowdown.
Steady performance recovery from August onwards.
Overall, performance wavering is minimal, meaning employee performance is stable and reliable across the year.

These steps will take you from a beginner to mastery level in Excel.
Enjoyed the article? Leave a thumbs up 👍

Beginner-friendly basics on Git

Marion Mukomi — Sun, 18 Jan 2026 13:46:05 +0000

Understanding Git
Git tracks every line you change, allowing you room to experiment freely.
Stages of Git
In git, your file travels through 3 main zones

Working directory- The actual files on your disk that you are currently working on.
Staging area- This is a data capture area. You put files here when they are ready to be captured together.
Repository- Once you commit, your changes are safely stored in the project's history.

Version Control System
Use case

Collaboration.
Storing all the file versions.
Restoring previous versions.
Figuring out what happened when a specific version is called later.

Benefits

Helps manage and protect source code from human error.
Keeps track of all modifications made.
Comparing earlier versions of the code.
Supports developers' workflow.

Configuring Git
Introduce yourself and configure GitHub to your Gitbash by running the following commands;

Check version

Configure name

3.Configure email

4.Check configured items

5.Generate SSH key
Check any existing SSH keys

In case of any existing keys, select the yes option to overwrite.
Generate a new SSH key

Press Enter to get the path that your key is saved on.
Reminder Note the path that the key is saved on for future references.
Start this key as your SSH agent
Press enter until you get a new line of code, and start that key as your SSH agent.

Add your SSH agent to GitHub

The key generated is your public key. The private key is saved on the path displayed earlier while generating an SSH key in step 5.

Connecting GitHub to your private key
Follow the following process to connect your GitHub to your private key;
Copy the generated key (all the code before the agent Id)
open GitHub> profile > settings > SSH and GPG key > add new ssh key > paste the ssh key copied > finish.

Test the connection
and type yes to confirm.

Pushing (Uploading)
When you have finished a task and committed it locally, you push it to the remote server so your teammates can see it.

Pulling (Downloading)
Before you start working, you should pull the latest changes. This grabs any new code your teammates have uploaded and merges it into your local version.

Collaboration: Push & Pull
Unless you are working alone, your code usually lives on a Remote server like GitHub or GitLab. This allows multiple people to work on the same project.

Basic Commands
Making a directory command. This creates a new folder(always name the folder after)
Change a directory command.
Exits the current folder.
Creates a file inside the folder created above.
Initialize GitHub.

Track your progress
Checks which files are modified. Use this often to see "where you are."
Moves a file into the Staging Area. This adds a new repository inside GitHub.
Permanently saves the staged changes to the Repository with a note explaining what you did.