From Concept to Test: Research vs Statistical Hypothesis

In research methodology (very important for MD/PhD proposal writing), Research hypothesis and Statistical hypothesis are related but not the same.

1. Research Hypothesis (Conceptual / Working Hypothesis)

A verbal, conceptual statement predicting a relationship between variables.

v  Written in words (not symbols)

v  Focus

• Explains expected relationship
• Based on theory, prior evidence, or logic

v  Example

High salt intake increases blood pressure among adults in Dharan.

Here:

• Independent variable → Salt intake
• Dependent variable → Blood pressure

It tells the expected relationship, but not how to test statistically.

2️. Statistical Hypothesis

A mathematical statement about population parameters used for statistical testing.

v  Written in symbols

v  Includes:

• Null hypothesis (H₀)
• Alternative hypothesis (H₁)

v  Same example converted to statistical form:

 

Research hypothesis:

High salt intake increases blood pressure.

Statistical hypothesis:

• H₀: μ₁ = μ₂ (Mean BP in high-salt group equals mean BP in low-salt group)
• H₁: μ₁ > μ₂ (Mean BP in high-salt group is higher)

Now it becomes testable using:

• t-test
• ANOVA
• Regression
• Chi-square (depending on variable type)

 

Key Differences

Feature	Research Hypothesis	Statistical Hypothesis
Form	Written in words	Written in symbols
Nature	Conceptual	Mathematical
Purpose	Guides study	Tested statistically
Includes H₀?	No	Yes (mandatory)
Used in	Introduction section	Methods & analysis section