How to Use and Format Numbers & Statistics in APA Style

Numbers and statistics are often used in academic writing to explore a topic or establish a point, especially in quantitative studies.

Many fields of social sciences, such as psychology, sociology, political science, and others, often rely on statistics and quantities to justify a point. 

The 7th edition of the APA format provides certain rules for writing numbers and providing statistics to maintain clarity and consistency.

So, what are the formatting standards for numbers and statistics? This guide provides a complete answer, so let’s get into it!

When to Use Numerals vs. Words for Number

Here are some general guidelines for when to use numerals versus words:

Use Numerals for

• Numbers 10 and above (e.g., 15, 103, 500).
  
• Measurements or quantities (e.g. 6 cm, 8 grams, 12 years old). The unit of measurement can be an abbreviation or word.
  
• Percentages (e.g., 25%, 75.5%). 
  
• Dates and times (e.g., December 3, 2023, 9:30 a.m.).
  
• Exact quantities and counts (e.g., 5 participants, 3 studies).
  
• Groups of three digits should be separated by a comma, (e.g. 1,000; 1,223,421)

Use Words for

• Numbers below 10 (e.g., one, five, nine).
  
• Ordinal numbers (e.g., first, third, tenth).
  
• Common fractions (e.g. one-tenth)
  
• In the beginning of a sentence, spell out the number regardless of size.

Rules for Decimals

When dealing with decimals in APA format, follow these guidelines: 

• Use a leading zero for decimals less than one (e.g., 0.75)
  
• Avoid including a leading zero before a decimal when the value being represented cannot exceed 1, such as in proportions or correlations.
  
• Provide means and standard deviations for data measured on integer scales (e.g., surveys and questionnaires) rounded to one decimal place. 
  
• For other means, standard deviations, correlations, proportions, and inferential statistics (such as t, F, chi-square), round to two decimal places. 
  
• Exact p-values should be reported to two or three decimal places (e.g., p = .006, p = .03). However, when p-values are less than .001, represent them as "p < .001."
  
• The principle for working with decimals in APA is this: Present fewer decimal digits for easy understanding. Round the numbers while retaining precision.

Statistics in APA

Statistics serve as the cornerstone of empirical research, highlighting patterns and relationships within data.

There are some rules for reporting statistics in APA style to ensure clarity in scholarly communication. Let’s dive into them!

Typeface and Formatting

Maintain a standard, non-italic typeface for Greek letters, common mathematical symbols, and abbreviations.

Boldface for Vectors and Matrices

Vectors and matrices are emboldened for emphasis:

When letters are used as statistical symbols, they should be italicized.

Parentheses for Values and Degrees of Freedom

When presenting statistical values, use parentheses to enclose them. This includes p-values, degrees of freedom, and statistical test results.

Confidence Intervals

Confidence intervals provide a range of plausible values. They are delineated by square brackets for precise representation:

Reporting Descriptive Statistics

When reporting descriptive statistics like means and standard deviations, streamline the presentation and avoid redundant information.

Reporting Statistical Tests

Chi-square Tests

For chi-square tests, include degrees of freedom, chi-square value, and p-value in parentheses.

Analysis of Variance (ANOVA)

When reporting ANOVA results, incorporate degrees of freedom, F-value, and p-value according to the example below:

Correlations

Here’s an example that shows how to report correlations with degrees of freedom, correlation coefficient (r), and p-value.

H4- Regressions

In regression analysis, include R-squared value, F-value (in brackets), degrees of freedom within brackets, and p-value.

In conclusion, 

Statistics and quantities are essential elements in academic studies. However, if not presented clearly, numbers can become a source of confusion or tools of academic dishonesty. 

The APA guidelines aim to counter the manipulation and misuse of statistics, but also promotes a standardized and clear way of presenting numerical values. By following these guidelines, you can ensure that your paper is accurate, precise, and easy to understand.

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