Normality and outliers
to uphold the assumption of normality, verify that either the
sample size is large enough (n > 30) or there is linearity in the
normal probability plot
to verify that there are no outliers, one can examine a box plot
although these
Math 106: Elementary Probability and Statistics
Chapter 1.1: Introduction to the Practice of Statistics
1
What is Statistics?
Statistics: The science of collecting, organizing, summarizing, and analyzing information in order to draw
conclusions or answer
Data Collection
results are presented with some measure of the amount of variability
identify the research objective
population- the group to be studied
individuals- an object within the population
Collect info needed
sample- a subset from the population
Inferential Statistics
population data can be difficult or even impossible to obtain
therefore, sample data are used to draw conclusions about the
population
the rest of this course will focus on how sample data are used to
draw conclusions
Samples differ
Ch. 3
Summarizing Data Numerically
a parameter is a descriptive measure from a population
a statistic is a descriptive measure from a sample
Measures of central tendency
mean (also called average)
the sum of all values in the data set, divided by the
numb
Cluster sampling
when groupings (or clusters) of individuals exist
within the population, randomly select some clusters
and sample all individuals within the selected
clusters
ex: dept of agriculture wishes to investigate
use of pesticides by farmers in e
Measures of Position
Measures of position describe the relative position of a
specific data value with respect to the entire data set.
these measures include:
z- scores
used to compare values of variables with
different centers and spreads to a standard
w
Ch. 6 Discrete Variables
Binomial Distribution Tables
Appendix Table 3: Binomial Probability Distribution for P(x)
Appendix Table 4: Cumulative Binomial Probability distribution, for P(
limited that you can only go up to 20 trials in these tables
mean (ex
5.2
The addition rule for disjoint events
two events are disjoint (or mutually exclusive) if they have
no outcomes in common
The Venn Diagram
P (A or B) = P(A) + P(B)
Ex. One samples patients randomly in a clinic. The event
that the patient is male is dis
4.2 Least-Squares Regression procedure
takes into account all individual data points and minimizes the
distances between the points and the line
the LSR line minimizes the of the residuals squared
residual is the vertical distance from the point to the li
Population proportion
likely the most frequently reported confidence intervals
polls, for example, often report a that a certain proportion (or
percentage) of individuals have a certain characteristic or opinion
assumptions:
normality: np (1 - p ) 10 (but
Math 106: Elementary Probability and Statistics
Chapter 2.1: Organizing Qualitative Data
1
Frequency Tables
Frequency: Number of occurrences.
Frequency Table: Lists the number of observations for each category of data.
Examples: Sample taken of 30 consume