Important Formulas
Z Score
x - mu divided by sigma
averaged Sum-of-Squares
What is Variance?
A scale of measurement where levels of measurement have sense of order but no assurance of equal distance between scores.
What is Ordinal?
numbers that summarize data from a Sample
What is a Statistic?
testable statement about the relationships among events of variables
What is a Hypothesis?
Variance Unbiased
sum of squares over n-1
the sum of any repetitively squared set of numbers
What is Sum of Squares?
A scale of measurement for which MODE is the only possible measure of central tendency.
What is Nominal?
numbers that summarize data for an entire Population
What is a Parameter?
term that refers to the differences amongst scores in a distribution of scores
What is Variability? or What is Dispersion
Sum of Squares
sigma notation (x - xbar) ^2
represents a range of values within which we are confident that some parameter of interest OR statistic may be found.
What is Confidence Interval?
A scale of measurement that has no sense of order or distance between scores.
What is Nominal?
the sampling distribution of the sample means approaches a normal distribution as the sample size gets larger
What is Central Limit Theorem?
purposefully matching the differences/extraneous variable(s) assigned to the experimental groups
What is Equivalent Groups?
Standard Deviation - Biased
square root of variance biased: sum of squares over N
represents the scores’ “average deviation from the mean.”
What is Standard Deviation?
A scale of measurement that is anchored on a true zero.
What is Ratio?
variables whose values do not result from measuring or counting.
What is Qualitative?
modified arithmetic mean based on how often a score occurs in the data set
What is Weighted Mean?
95% Confidence Interval
mu +or- 1.96 * (sigma/√n)
This score can only be calculated when you know Mu and sigma in the population of scores, it describes a raw score that is adjusted for the mean and standard deviation of the distribution.
What is Z score?
A scale of measurement where there is equal distance between scores, when points are evenly spaced along a scale.
formal statement about what is believed to be true about a set of events or variables
What is a Theory
the percentage of scores that are at or below an identified score
What is Percentile Rank?