Hypothesis
A testable statement that predicts a relationship between two or more variables.
What is a hypothesis?
This mathematical notation, which always equals zero, represents the sum of the deviations of each data point from the mean.
What is Σ(X – M)?
A simple classification system, such as gender or hair color, is an example of this scale of measurement.
What is a nominal scale?
The variable in a study that is changed or manipulated by the researcher.
What is the independent variable?
This is a small, representative subgroup of individuals chosen from a larger group of interest.
What is a sample?
A hypothesis about a specific cause-and-effect relationship between variables would typically lead a researcher to use this type of research design.
What is an experimental design?
The square root of this value gives you the standard deviation.
What is Sum of Squares (SS) or Σ(X – M)2?
This scale is used when data has a specific order but the intervals between points are not equal, such as a ranking of favorite foods.
What is an ordinal scale?
This defines a variable in terms of the exact procedures used to measure or manipulate it, making the research replicable.
What is an operational definition?
The process of selecting individuals to participate in a study, which can be done in various ways to ensure a sample is representative.
What is sampling?
A researcher hypothesizes that exposure to sunlight increases mood. In this hypothesis, "mood" is this type of variable.
What is the dependent variable?
This value indicates how many standard deviations a data point is from the mean, allowing for comparisons across different distributions.
What is a standardized score (or z-score)?
The consistency or stability of a measurement tool, ensuring it produces similar results over repeated uses.
What is reliability?
This is established when one variable is shown to directly produce a change in another variable, a claim that can only be made with an experimental design.
What is a cause and effect relationship?
This describes a frequency distribution where the data is symmetrical, with the highest frequency in the middle and frequencies tapering off evenly to the left and right.
What is a normal distribution?
This type of variable is often associated with a correlational study and cannot be directly controlled or assigned by the researcher.
What is a subject variable (or non-manipulated variable)?
If a person's score is at the 85th percentile, it means they scored better than this percentage of the people in the sample.
What is 85%?
A measure is said to have this quality if it actually measures what it is intended to measure.
What is validity?
This statistical relationship measures how two variables move together, while the associated analysis provides a mathematical equation to describe and predict that relationship.
What are correlation and regression?
If a researcher wanted to test a hypothesis about all college students, this would be the larger group of interest.
What is a population?
Due to the nature of an hypothesis, formulating a hypothesis that is too broad, such as "all people are happy," makes it difficult to define these two key components, which are essential for conducting a valid experiment.
What are the independent and dependent variables?
One of these is a measure of the average distance of scores from the mean, while the other, which refers to the denominator (n−1), is the number of independent values used in its calculation for a sample.
What are standard deviation and degrees of freedom?
The primary difference between these two measurement scales is that one has a true zero point, indicating a complete absence of the measured variable, while the other does not.
What are ratio and interval scales?
In the equation Y=mX+b, the letters X and Y are examples of this, representing variables.
What is notation?
One of these types of variables represents numerical values that can be counted or measured, while the other represents named categories or labels.
What are quantitative and categorical variables?