MMW Flashcards
Two Branches of Statistics
Descriptive Statistics & Inferential Statistics
Using the data gathered on a group to describe or reach conclusions about the same group
(E.g. class average, range of scores in an exam)
Descriptive Statistics
A researcher gathers data from a sample and uses thestatistics generated to reach conclusions about thepopulation from the sample drawn.
Inferential Statistics
Two Types of Variable
Qualitative & Quantitative
TWO KINDS OF Quantitative Variables
Discrete & Continuous
- Countable
- Data are obtained by counting
Discrete
Can assume an infinite number of values in an interval between any two specific values
Continuous
Four Levels of Data Management
Nominal
Ordinal
Interval
Ratio
4 TYPES OF Data Collection Method
Survey
Direct Observation
Experiment method
Registration Method
lowest level of data management- for identification and classification
Nominal
use to reflect some rank or order ofindividual or objects
Ordinal
zero is arbitrary (eg. Temperature)
Interval
highest level of data measurement
Ratio
zero is absolute (e.g. height)
Ratio
makes use of questionnaires (can be telephone, email, personal)
Survey
data regarding the behavior,attitudes, values, or cultural patterns of individuals are gathered
Direct Observation
objective is to determine cause and effect relationship
Experiment method
provide information to comply with a law or policy
Registration Method
Different Forms of Presentation of Data
Textual
Tabular
Graphical Presentation
consists of bars either vertically or horizontally and usually constructed in comparative purposes
Bar Graph
shows relationship between one or more sets of quantities; best used to establish trends
Line Graph
used to represent quantities that make up a whole
Pie Chart
is a single score or value that stands for or represents a group of scores or values of the items in a set of data.
MEASURES OF CENTRAL TENDENCY
3 TYPES OF MEASURES OF CENTRAL TENDENCY
Mean
Median
MODE
The sum divided by the count
Mean ( X )
is a positional measure and the middlemost value in the distribution
Median ( Md )
is the value or item in a distribution which occurs most frequently or has the highest frequency
Mode ( Mo )
Divides the distribution in 100 parts
PERCENTILE
Divides the distribution into 4 parts
Quartiles
also known as the standard score is the number of standard deviations that a number is above or below the data set
Z score
BELL SHAPE CURVE
Normal Distribution
SYMMETRIC ABOUT VERTICAL LINE
Normal Distribution
LOCATED AT THE HIGHEST POINT
CENTER
THE MEAN,MEDIAN,MODE ARE
EQUAL
TOTAL AREA IS
1 OR 100%
the data lie within 1 standard deviation of the mean.
68%
the data lie within 2 standard deviations of the mean.
95%
the data lie within 3 standard deviations of the mean.
99.7%
measures the relationship between bivariate data.
Correlation
are data sets in which each subject has two observations associated with it.
Bivariate data
measures an outcome or result of a study.
response variable (dependent variable)
is a variable that we think explains or causes changes in the response variables.
explanatory variable (independent variable)
Is an approach for modeling the relationship between a dependent variable (outcome) and one or more explanatory variables.
Linear regression
The case of one explanatory variable is called
simple linear regression.
is a graph of plotted points showing the relationship between two numerical variables.
Scatterplot
Graphing the data in the scatter plot gives
preliminary information about the shape
The range of values of the correlation coefficient is
form -1 to +1.
It means that, when X increases, Y also increases and when X decreases, Y also decreases.
POSITIVE correlation
High scores in distribution X are associated with low scores in distribution Y. Low scores in distribution X are associated with high scores in distribution Y.
NEGATIVE correlation
There is no association between the scores in distribution X and distribution Y. No single line can be drawn that best fits to all points or no discernable pattern can be formed.
ZERO CORRELATION
It is indicated as r x y also known as Pearson Product-Moment Correlation Coefficient in honor of Karl Pearson who developed the formula.
CORRELATION
