I want a large pistachio soy latte for my Systems definition

Published 2 months ago • 3 min read

Alex Toth

Understand and apply this! You’ll leap from a beginner to respectable Engineer.

A double espresso would've been more suitable for that need?

I'm in the Coffeshop again.

My Chromebook sits serenely on the table and my flat white coffee near. I can't live without coffee and this ritual helps me think.

Wanna see it?

I'm writing this for you and preparing for a tough day. Thinking of all the things I need to do.

Why I'm telling you this?

Well, I was interrupted …

This girl enters and goes straight to the barista:

"I want a large pistachio soy latte, 3 shots, not too hot, with 3 sugars. I slept little and badly; I need to wake up fast."

My brow goes up. That caught my attention. So I listen to the conversation.

Why? - you ask. The WHY is very important. Read on you'll see why...

Because I'm a Systems Engineer. It flows in my veins. I'll tell you about it in a moment.

But first - what happened?

She got the latte. She sits down alone with her phone. Yeah, talking to no one.

We all know you need to talk to wake up, no? That's what my ex used to say ... am I getting confused?

Ten minutes pass and she's still knackered. Twenty, twenty-five minutes:

I can tell she's sleepy and can't think straight. Head in hands. She didn't even finish the cup!

She's still sleepy and now she's pissed!

"Did you put my espresso shots into it? I hope you didn't use decaf! What kind of coffee are you making? This does nothing..."

Now everyone is looking as she complains loudly to the barista!

Why this matters? It's what caught my attention initially:

She came in with very specific requirements for her coffee. When all she needed was to wake up fast! But she failed to consider that. And the barista just executed without asking.

He didn't validate her requirements! He's not a System Engineer ...

When all she needed was to wake fast!

A double espresso would've been more suitable for that need.

So how is this related to Systems Engineering?

I'll tell you. It has everything to do with SE. It's its blood. I know that you think you know what I know you know, but ….

Hear me out.

Did you know there’s a world of difference. Some fundamental and some more subtle.

Let me show you.

In engineering recognizing the difference between needs and requirements is crucial. It underscores the importance of thorough needs analysis before jumping to specific technical requirements.

This sadly is not done enough or properly.

Needs and Requirements are two distinct but related concepts in systems engineering. Here's a simple explanation of their differences:

Needs are the high-level user-oriented desires or capabilities that stakeholders want from a system.
Requirements, on the other hand are the technical, detailed specifications that describe how the system will meet those needs.

Think of it like planning a vacation:

1. Needs: "I want a relaxing beach getaway with good food."

2. Requirements: "The hotel must be within 100 meters of the beach, have a 4-star rating, and include at least two restaurants on-site."

According to INCOSE and ISO 15288 the process of defining needs is called "Stakeholder Needs and Requirements Definition."

This process aims to identify what users and other stakeholders want the system to do in their environment.

It's like asking your family what they want from the vacation.

The "System Requirements Definition" process then takes these needs and transforms them into technical specifications that engineers can work with.

This is similar to a travel agent taking your family's wishes and turning them into specific hotel bookings, flight arrangements, and activity schedules.

Requirements specify the system characteristics, attributes, functions and performance that will meet the stakeholder needs.

A requirement is a “Statement that identifies a product or process operational, functional, or design characteristic or constraint, which is unambiguous, testable or measurable, and necessary for product or process acceptability”.

Don’t worry - I’m done with jargon and quoting stuff at you.

Simpler:

A requirement is a precise specification of what the system must be or do. And how well it needs to do it.

In a way that is quantifiable and measurable so we can prove it does it. A typical way of proving that is by testing.

It specifies what the system must do so that it fulfils what the Stakeholders need it to do.

So they now have a capability (system) that they can use it to resolve the problem that prompted this system to come into existence.

It fulfils its purpose. We all need to, no? …

The key differences are:

Level of detail: Needs are broad, while requirements are specific.
Language: Needs use stakeholder language, while requirements use technical language.
Purpose: Needs express desired capabilities, while requirements define how to achieve them.

By clearly distinguishing between needs and requirements systems engineers can ensure they're building a system that truly meets stakeholder expectations while providing clear technical guidance for implementation.

A quick visualisation below the place of needs and requirement definition in the Project Lifecycle.

Please observe it’s all iterative. There is no Waterflow in complex projects.

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