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Andrew Ferris

Don't Fear the Math: A Simple Guide to Standard Deviation for Small Businesses

Graphical representation of standard devitation

Hey there, fellow small business owner! I know terms like "standard deviation" might sound like they're straight out of a statistics textbook (yawn), but stick with me. I promise it's not as intimidating as it sounds, and it can actually be a game-changer for your business.


Standard Deviations: A collection by Marcus Damanda
How most of us think about Standard Deviation

What is Standard Deviation?

Simple Definition

Standard deviation is just a fancy way of measuring how much your numbers vary from the average. Think of it as the "consistency meter" for your business data.

 

Picture this: You own a cozy café, and you start tracking how long customers wait for their coffee each day. If most folks wait about the same amount of time—say, 5 minutes—then your service is consistent, and the standard deviation is small. But if some customers get their latte in 2 minutes while others wait 15, your wait times are all over the place, and the standard deviation is bigger than a triple-shot espresso.

 

Breaking It Down

  • Mean (Average): Add up all your numbers and divide by how many numbers you've got. Simple math, nothing scary.

  • Variability: How much do your numbers differ from each other? Are they bunched together like a tight-knit family, or spread out like toppings on a pizza gone wrong?

  • Standard Deviation: This number tells you, on average, how far each number is from the mean. A small standard deviation means your data points are huddled close to the average—a big win for consistency. A large one? Well, it might be time to investigate what's causing the chaos.

Why is Standard Deviation Important for Your Business?

Understanding Variability

Variability isn't just a fancy word; it's the heartbeat of your business operations. Knowing how much things fluctuate helps you:

  • Spot Trends and Patterns: Are your sales dipping every Thursday? Is there a spike in customer complaints at the end of the month? Standard deviation can highlight these quirks.

  • Improve Processes: If project completion times are all over the map, maybe it's time to streamline your workflow.

  • Predict Problems Before They Happen: High variability might be the canary in the coal mine, signaling issues that could escalate if left unchecked.

 

Consistency Matters

Let's be real—customers love consistency. Imagine going to your favorite pizza place and not knowing if you're getting a delicious pie or a burnt disaster each time. Not cool, right?

Here's why consistency is a big deal:

  • Customer Satisfaction: Consistent service keeps your customers happy and coming back for more. Happy customers = repeat business = more cha-ching.

  • Financial Planning: If your sales numbers are as unpredictable as the weather, budgeting becomes a nightmare. Knowing the standard deviation helps you plan better.

  • Employee Morale: Your team will appreciate knowing what's expected and not dealing with constant chaos.

 

Risk Management

High variability introduces uncertainty, which is the arch-nemesis of good business. By keeping an eye on standard deviation, you can:

  • Reduce Surprises: No more nasty shocks when the monthly reports come in.

  • Make Informed Decisions: Should you expand? Hire more staff? Cut costs? Knowing the variability in your key metrics helps you make smarter choices.

 

Competitive Edge

Let's face it—business is a game, and understanding your stats gives you a leg up on the competition. While others are fumbling in the dark, you'll be making data-driven decisions.

Businessmen riding rockets on a track
AI fever dream representation of competitive edge

How to Calculate Standard Deviation Easily

Alright, let's roll up our sleeves and dive into how to calculate standard deviation. Don't worry—you don't need to be a math whiz. With tools like Excel or Google Sheets, your computer can do the heavy lifting.

 

Step-by-Step Guide Using an Example

Suppose you own a small coffee shop, and you've tracked the number of customers each day for a week:

  • Monday: 50 customers

  • Tuesday: 60 customers

  • Wednesday: 55 customers

  • Thursday: 65 customers

  • Friday: 70 customers

  • Saturday: 80 customers

  • Sunday: 40 customers

Let's calculate the standard deviation of your daily customer count.

 

Step 1: Enter Your Data

In Excel or Google Sheets, enter your data in a column (e.g., cells A1 to A7):

A

50

60

55

65

70

80

40

 

Step 2: Calculate the Mean (Average)

In an empty cell, type:

  • For Excel: =AVERAGE(A1:A7)

  • For Google Sheets: =AVERAGE(A1:A7)


Press Enter. The mean should be 60.

A

50

60

55

65

70

80

40

=AVERAGE(A1:A7)

*the number will be 60

 

Step 3: Calculate the Standard Deviation

In another empty cell, type:

  • For Excel: =STDEV.S(A1:A7)

  • For Google Sheets: =STDEV(A1:A7)


Press Enter. The standard deviation should be approximately 13.23.

A

50

60

55

65

70

80

40

60

=STDEV.S(A1:A7)

*the number will be 13.23

Interpreting the Results

  • Mean Customers per Day: 60

  • Standard Deviation: About 13 customers

 

This means that on any given day, the number of customers varies by about 13 from the average. Some days you'll have more than 60 customers, some days less, but most days will fall within this range.

 

Why It Matters

  • Staffing: Knowing this variability helps you schedule staff more effectively. If Saturdays see a big jump in customers, you'll want more hands on deck.

  • Inventory: It guides how much inventory to stock each day to meet customer demand without overstocking.

 

Practical Tips

  • Double-Check Your Data: Ensure all your numbers are entered correctly. Typos can throw off your results.

  • Use Templates: Plenty of free templates online have built-in formulas if you're not comfortable setting up your own spreadsheet.

  • Learn from Tutorials: If you're new to Excel or Google Sheets, there are tons of tutorials on YouTube to help you out.

 

Real-World Applications of Standard Deviation

Let's dive into some real-world scenarios to see how this powerful tool can make a tangible difference.

Clerk hands customer a bag in a retail store

 

Retail and Service Businesses: Tracking Customer Wait Times

 

Scenario:

You own a café and notice that sometimes customers get their orders super fast, and other times they're waiting longer than a slow brew.

 

How to Use Standard Deviation:

  • Collect Data: Record the time it takes from when a customer places an order to when they receive it over a month.

  • Calculate the Mean and Standard Deviation: Use Excel or Google Sheets to find the average wait time and how much it varies.

 

Actions to Take:

  • Identify Bottlenecks: Is the kitchen getting slammed during peak hours? Maybe the barista needs more training.

  • Optimize Staffing: Adjust staff schedules to ensure enough hands during busy times.

 

Analyzing Daily Sales

Scenario:

Your sales numbers are as unpredictable as the weather. Some days you're packed, and others it's a ghost town.

 

How to Use Standard Deviation:

  • Collect Data: Record daily sales figures over several months.

  • Calculate Standard Deviation: See how much daily sales fluctuate from the average.

 

Actions to Take:

  • Marketing Efforts: Boost promotions on slower days to attract customers.

  • Inventory Management: Adjust orders based on sales variability to reduce waste.

 

Freelancers and Consultants: Project Completion Times

Scenario:

As a freelance graphic designer, some projects take you twice as long as others.

 

How to Use Standard Deviation:

  • Collect Data: Record how long each project takes.

  • Calculate Standard Deviation: Understand the variability in your project timelines.

 

Actions to Take:

  • Set Realistic Deadlines: Use data to inform clients about expected timelines.

  • Project Scoping: Better define project requirements upfront to avoid surprises.

 

Income Predictability

Scenario:

Your monthly income swings wildly, making budgeting a rollercoaster ride.

 

How to Use Standard Deviation:

  • Collect Data: Track your income month by month over the past year.

  • Calculate Standard Deviation: See how much your income varies.

 

Actions to Take:

  • Financial Planning: Build a savings buffer for lean months.

  • Diversify Services: Offer a mix of high-paying, longer-term projects and quick gigs to stabilize income.

 

Healthcare and Education: Patient Satisfaction Scores


People waiting in a doctor's office
Free hint for practices: hire someone who can do scheduling

Scenario:

Your patient satisfaction surveys show a wide range of responses.

 

How to Use Standard Deviation:

  • Collect Data: Gather scores from patient feedback forms.

  • Calculate Standard Deviation: Determine variability in satisfaction.

 

Actions to Take:

  • Staff Training: Address areas where patients report inconsistent experiences.

  • Process Improvements: Streamline check-in procedures or reduce wait times.

 

Student Performance

Scenario:

Test scores among students vary widely, affecting overall class performance.

 

How to Use Standard Deviation:

  • Collect Data: Record student test scores.

  • Calculate Standard Deviation: Understand performance variability.

 

Actions to Take:

  • Tailored Instruction: Provide extra help to students who are struggling.

  • Curriculum Adjustment: Re-evaluate teaching methods or materials.

 

Key Benefits Across Examples

  • Improved Decision-Making: Make informed choices based on data, not just gut feelings.

  • Enhanced Efficiency: Identify areas where processes can be streamlined.

  • Risk Mitigation: Spot potential issues before they become big problems.

  • Better Resource Allocation: Use your time, money, and people where they're needed most.

 

Conclusion

Using standard deviation in your business isn't just number crunching; it's about unlocking insights that can drive growth, improve customer satisfaction, and give you a competitive edge. It's a powerful tool that can help you navigate the complexities of running a small business with greater confidence and clarity.

 

Ready to Take Action?

  • Start Small: Pick one area of your business—like daily sales or customer wait times—and calculate the standard deviation.

  • Set Goals: Use your findings to set measurable goals for improvement.

  • Monitor Progress: Regularly track and analyze your data to see how changes impact variability.

 

Remember, the journey of a thousand miles begins with a single step—or in this case, a single calculation. You've got this!

 


Andrew Ferris, Owner of Sirref Marketing in Greenville, NC

Andrew Ferris is the owner of Sirref Marketing. We help small local businesses in Eastern NC become healthier and more efficient inside and out!



Greenville, NC and neighboring area business owners:

Let's connect! Book a time with me to see how we can partner to help your business thrive inside and out.

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