Misc. Equations/Definitions Flashcards
Parameter
A measurement of a population
Statistic
A measurement of a sample
What does “Remember your SOCS” stand for?
Shape
Outliers
Center
Spread
How do we find the middles from a histogram?
∑(median of each class * frequency)/total count
What symbol do we use for population mean?
μ
What symbol do we use for a sample mean?
x̄
Is the mean resistant to outliers?
No
Is the median resistant to outliers?
Yes
IQR
Interquartile Range=Q3-Q1
1.5 IQR Rule
Possible outliers are outside the interval [Q1-1.5IQR, Q3+1.5IQR]
Standard Deviation
How far points are away from the mean, average. Distance of the data points from the mean.
Is there more variability in a population or a sample?
Sample
Variance
(Standard Deviation)^2
Is the standard deviation resistant to skewness?
No
Relative Frequency
The proportion of data to the left of a point.
Z-Score
Number of standard deviations away from the mean.
68-95-99.7 Rule
In a normal distribution,
aprx. 68% of data is within one standard deviation of the mean.
aprx. 95% of data is within two standard deviations of the mean.
aprx. 99.7% of data is within three standard deviations of the mean.
How do we transform from X(normal) to Z(std. normal)?
Z=(X-μ)/σ
Explanatory Variable
Attempts to explain the observed outcomes or variation in the other variable.
Response Variable
Measures the outcome of the study
A statement is always…
y vs x / response vs explanatory
Median Trace
Divide data into classes (vertical strips) of the same width, & then find the median of each class and connect the medians with segments.
