You Can Do This.
Welcome to Methodology Pro. Research is often presented as an insurmountable wall of mathematics. It is not. It is a logic puzzle.
You don't need to be a statistician to be a researcher. You just need a system. This tool is your reference system. By the end of this session, you will know exactly what to look for, how to run it, and how to write it up. Take a deep breath. You got this.
Pocket Data
We use this tiny dataset (N=3) so you can verify the logic instantly.
Finding "The Gap"
Research isn't just about collecting data; it's about solving a missing piece of a puzzle. A "Gap" is the space between what we know and what we need to know. Select a domain and a logic type to see how a hypothesis is constructed.
The Hierarchy of Variables
Variables are the building blocks of research. You must identify them correctly to choose the right test. We follow the NOIR framework.
Categorical (Qualitative)
Nominal
Names / Labels. No mathematical value. No order.
Ex: Eye Color, Group (Placebo/Drug).
Ordinal
Rank Order. A strict order exists, but the distance between points is unknown.
Ex: Race finish (1st, 2nd, 3rd), Likert Scales (Agree/Disagree).
Continuous (Quantitative)
Interval
Equal Distances. The gap between 1 and 2 is the same as 3 and 4. No "True Zero."
Ex: Temperature (Celsius/Fahrenheit), IQ Scores.
Ratio
True Zero. Zero means "absence of the variable." Allows for multiplication/division.
Ex: Height, Time, Reaction Time, Weight.
Experimental Roles
Independent (IV)
The Cause. The variable you manipulate or group by.
"Does Drug A affect Stress?"
Dependent (DV)
The Effect. The outcome variable you measure.
"Does Drug A affect Stress?"
Independent Samples T-Test
The Narrative: Signal to Noise
A T-Test compares the Signal (the difference between the two group means) against the Noise (the variance/spread within the groups). If the Signal is much louder than the Noise, we conclude the groups are truly different.
R Syntax
SPSS Steps
Analyze > Compare Means > Independent-Samples T Test.
Test Variable: Stress. Grouping Variable: Group.
One-Way ANOVA
The Narrative: Variance Partitioning
ANOVA argues that the variance between the 3 groups is greater than the variance within them. If we ran 3 separate T-Tests, our error rate would inflate to ~15%. ANOVA keeps it at 5%.
TukeyHSD(model)
Analyze > Compare Means > One-Way ANOVA. (Post Hoc: Tukey).
Correlation & Regression
The Narrative: Association
We ask: "Do these two variables move together?" It is non-directional. X is associated with Y, but X might not cause Y.
Analyze > Correlate > Bivariate.
Mediation Analysis
The Narrative: The Process
We argue that the effect of Drug (X) on Stress (Y) is not direct, but travels through Sleep (M).
Operationalization: We test the "Indirect Effect" (path a * path b). Normal theory assumes this value is normally distributed, but it is usually skewed. Therefore, we MUST use Bootstrapping.
R Syntax (lavaan)
model <- '
Sleep ~ a*Drug
Stress ~ b*Sleep + c*Drug
indirect := a*b
'
# Run SEM with Bootstrapping
fit <- sem(model, data=data, se="bootstrap")
SPSS Steps (PROCESS Macro)
1. Analyze > Regression > PROCESS v4
2. Y: Stress, X: Drug, M: Sleep.
3. Options > Check "Bootstrap inference for indirect effects".
Report Generator
Select your test to build the specific write-up components for a professional manuscript.
Final Abstract (APA Format):
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Copy/Paste Ready:
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