Display A Calculation Using Stata

A professional utility to evaluate Stata mathematical expressions and statistical output commands.

What is Display a Calculation Using Stata?

To display a calculation using stata refers to the practice of using the display command (often abbreviated as di) to evaluate mathematical expressions, scalars, or local and global macros directly in the Stata results window. This functionality acts as a built-in calculator for researchers, allowing them to perform quick checks, derive p-values from test statistics, or format output for reporting.

Commonly, users who need to display a calculation using stata are performing post-estimation analysis, such as calculating a confidence interval manually or determining the ratio between two coefficients. One common misconception is that display is only for text; in reality, it is a powerful expression evaluator that can handle complex nested functions and system variables.

Display a Calculation Using Stata Formula and Mathematical Explanation

The mathematical evaluation follows standard algebraic precedence (PEMDAS/BODMAS). When you display a calculation using stata, the software first resolves functions, then powers, then multiplication/division, and finally addition/subtraction.

Variable	Stata Syntax	Mathematical Meaning	Typical Range
Addition	+	Sum of two values	-∞ to +∞
Subtraction	-	Difference between values	-∞ to +∞
Multiplication	*	Product of values	-∞ to +∞
Division	/	Quotient of values	Divisor ≠ 0
Exponentiation	^	Power of a number	N/A

Practical Examples (Real-World Use Cases)

Example 1: Calculating a Z-Score

Suppose you have a coefficient of 2.5 and a standard error of 0.8. To display a calculation using stata for the Z-score, you would type:

display 2.5 / 0.8

The output would be 3.125. This allows the researcher to quickly gauge statistical significance before running a formal test.

Example 2: Annualizing a Growth Rate

If you have a monthly growth rate of 0.01 (1%), and you want to see the compounded annual growth rate, you would use:

display (1 + 0.01)^12 – 1

The result (approximately 0.1268) shows a 12.68% annual return, demonstrating the precision of how to display a calculation using stata.

How to Use This Display a Calculation Using Stata Calculator

1. Enter Value 1: This is typically your numerator or the base of your exponent.
2. Enter Value 2: This is your divisor, subtrahend, or exponent.
3. Select Operation: Choose from the dropdown to define the relationship between the two numbers.
4. Review Results: The primary result shows the computed value. The “Generated Stata Syntax” section provides the exact code you can paste into your Stata command line.
5. Interpret Chart: The visual distribution chart shows where your result sits in a standardized context.

Key Factors That Affect Display a Calculation Using Stata Results

• Precision Level: Stata typically displays results in a default format, but you can change this using %fmt.
• Floating Point Math: Like all software, Stata uses binary floating-point representation, which can occasionally lead to tiny rounding differences in extremely large or small numbers.
• Operator Precedence: Using parentheses is vital. di 2+3*4 results in 14, whereas di (2+3)*4 results in 20.
• System Variables: You can include variables like _N (number of observations) or _pi in your calculations.
• Missing Values: If a calculation involves a missing value (.), the result of the display a calculation using stata will almost always be missing.
• Local/Global Macros: If displaying a macro, you must use the correct prefix (`local' or $global).

Frequently Asked Questions (FAQ)

Can I display a calculation using stata for text and numbers together?

Yes, you can use display "The result is " 2+2 to combine strings and math.

What is the difference between ‘display’ and ‘list’?

display calculates and shows a single line of output, while list shows the contents of the dataset variables.

How do I round the result in the display command?

Use the round function: display round(2.567, 0.01) to get 2.57.

Does Stata follow standard mathematical order of operations?

Yes, it follows the standard algebraic hierarchy (Powers, Multiplication/Division, Addition/Subtraction).

How can I calculate a p-value using ‘display’?

For a normal distribution, use display 2*(1-normal(abs(z))) where z is your calculated statistic.

Can I use ‘di’ for logarithms?

Yes, display ln(10) or display log10(100) are valid mathematical expressions in Stata.

What happens if I divide by zero in Stata?

Stata will return a missing value (.) and often indicate “division by zero” in the output window.

How do I display a calculation using stata for a specific observation?

You can use subscripts, such as display variable[10] * 2, to calculate using the value from the 10th row.

Related Tools and Internal Resources

• Stata DI Command Guide: A deep dive into all flags and formatting options for the display command.
• Advanced Math Expressions: Learn how to use complex functions like exp(), sqrt(), and logit().
• Stata Statistical Calculator: Online tool to verify your Stata outputs against standard statistical tables.
• Stata Programming Basics: Using display in loops (foreach/forvalues) and programs.
• Stata Variable Display: Formatting how your variables appear in the browser and results window.
• Stata Statistical Output: Understanding the standard tables generated by regress and summarize.