Stat exam 1
maximum positive correlation
+1.00
minimum negative correlation
-1.00
Q3
75th percentile
Q2
= observation at the 50th percentile
Numerical / Quantitative (Quantity
Discrete and Continuous
Ordinal
Has a natural ordering, economic status, with three categories (low, medium and high), educational experience (with values such as elementary school graduate, high school graduate, some college and college graduate)
skewed left
Mean < Median
skewed right
Mean > Median
symmetric
Mean ≈ Median
Median
Middle number
5 number summary
Min, Q1, Median, Q3, Max
nominal
Name of category, Gender (female/male), hair color (blonde, brunette, red
Categorical(category)
Nominal and ordinal
IQR
Q3 - Q1
opperational definition
a universally accepted meaning that is clear to all associated with the analysis
Population
all items/individuals about which you want to reach conclusions (described by PARAMETERS
mean
average
Judgment
collect a sample that an "expert" thinks is representative of the population
Convenience
collect the sample that is easiest to access
Discrete
distinct cutoffs between values, Number of friends, number of children, number of courses
Cluster
divide N items in the frame into clusters and take a random sample of the clusters. Study all items in the cluster
Stratified
divide frame into groups (strata). Take a simple random sample from each strata
coefficient correlation
https://www.socscistatistics.com/tests/pearson/default2.aspx
z-score
is equal to the difference between a value and the mean, divided by the standard deviation
Sample
items/individuals (from the population) which are selected for analysis (items/individuals about which you collect data) (described by STATISTICS
RANGE
largest value - smallest value = maximum - minimum
Q1
observation at the 25th percentile
Continuous
on a continuum, Height, weight, time
y ̂=b0+b1x
regression line
Probability Samp
select items/individuals/units for the sample based on known probabilities (GOOD!)
Non-Probability Sample
select items/individuals/units for the sample without knowing their probabilities of selection (BAD!)
b1
slope
standard deviation
square root of the variance
Volunteer
subjects choose to participate in the study
Systematic
uses a systematic method k=N/n (i.e. n groups of k items such as, every 10th person) to select the sample
Mode
values that occur most often
b0
y-intercept
•Z is a UNIT OF MEASURE of the number of standard deviations
•If positive, ABOVE the mean •If negative, BELOW the mean
•Z helps identify outliers
•In general, Z < -3.00 or Z > 3.00 indicates an outlier value
Ordered array
•arranges the values of a numerical variable in rank order (smallest value to largest value) Array è Ordered Array
POPULATION mean (μ
•is the sum of values in a POPULATION divided by the number of values in the POPULATION:
Variation
•measures the amount of dispersion, or scattering from a central value. That is, how spread out are the data values
