Simply Statistics
Math vs. Psychology Stats
MATHEMATICS
Independent
Variable
A variable in an equation that may have its value freely chosen without considering values of any other variable.
PSYCHOLOGY
Independent
Variable
A measure that is manipulated in a study to see how it impacts or influences another measure (dependent variable)
MATHEMATICS
Dependent Variable
A variable that changes based on the selected values of the independent variable.
PSYCHOLOGY
Dependent Variable
A measure that is impacted or influenced by the independent variable.
MATHEMATICS
p-Value
The probability of seeing a result at least as extreme as the actual result for when the Null Hypothesis is true.
PSYCHOLOGY
p-Value
The probability that the researcher found a significant difference in the data when there actually isn't one.
If the p value is less than the alpha value
(p < .05), then you can reject the null hypothesis (or be confident that there is a significant difference in your data).
MATHEMATICS
Nominal Data
Categorical data without true numerical value. Groups are allocated to distinct categories regardless of any measuring value.
PSYCHOLOGY
Nominal Data
This is categorical data without true numerical value. This is usually seen in groups like male or female; or Republican, Democrat or independent.
MATHEMATICS
Ordinal Data
This data has an order to it in which there is an uneven change between individual data points.
PSYCHOLOGY
Ordinal Data
This data has an order to it, but the difference within the order might not be even (such as runners’ finishing time in attaining first, second, or third)
MATHEMATICS
Interval Data
Has an order to it in which there is an even change between data points, but there is not an absolute zero.

PSYCHOLOGY
Interval Data
The spacing between each number is even, but has no absolute zero (e.g. Fahrenheit; there is no “real” 0)
MATHEMATICS
Ratio Data
Has an order to it in which there is an even change between data points, but there is an absolute zero.

PSYCHOLOGY
Ratio Data
The spacing is even between each number, and an absolute 0 exists (e.g. weight, age, or height)

MATHEMATICS
Positive Correlation
When two variables react equally to changes, either both decrease or both increase

PSYCHOLOGY
Positive Correlation
The relationship between two variables that increase and decrease together.
MATHEMATICS
Negative Correlation
When two variables react in an equal but opposite way to changes. As one variable increases, the other will decrease, or vice versa
PSYCHOLOGY
Negative Correlation
The relationship between two variables when one is increasing and the other is decreasing (the opposite is true)