INTRODUCTION TO STATISTICS Flashcards
What is statistics
science of collecting, organizing, presenting, analyzing, and interpreting data to assist in making more effective decisions
used to describe a group’s characteristics
descriptive statistics
Types of statistics
- Descriptive Statistics
2. Inferential Statistics
Inferential statistics
uses statistical tools to predict and infer something
Other definition of descriptive statistics
method of organizing, summarizing, and presenting data in an informative and descriptive way.
Population
entire set of individuals or object of interest
A portion or part of the population of interest
Sample
It should have the same characteristics as the population it is representing
Sampling
Two ways a sampling can be
- with replacement
2. without replacement
With replacement
a member of the population can be chosen more than once (picking a candy from the bowl)
Without replacement
a member of the population can only be chosen once (lottery ticket)
Methods of sampling
- random
2. nonrandom
Random sampling method
each member of the population has an equal chance of being chosen
Non random sampling method
a biased sampling technique
What are the four random sampling methods
- Simple random sample
- Stratified sample
- Cluster sample
- Systematic sample
Each sample of the same size has an equal chance of being chosen
simple random sample
What is stratified sample
divide a population into groups called strata and then take a sample from each stratum
What is cluster sample
divide the population into strata and then randomly select some of the strata. All members from these strata are in the cluster sample
Systematic Sample
Randomly select a starting point and then take every n-th piece of data from a listing of the population
Purposive sampling
one will be chosen based on their knowledge of the information required by the researcher
identify the stratums and their proportions as they are presented in the population
Quota Sampling
Convenience sampling
resorted by the researchers who need the information the fastest way possible. it only includes people who are easy to reach
Snowball sampling
relies on referrals from initial subjects to generate additional subjects.
They are usually obtained by counting or measuring items
Statistical data
Two types of statistical data
- Primary data
2. Secondary data
What is a primary data
collected specifically for the analysis desired
what is secondary data
data that have been already compiled and are available for statistical analysis
It has a numerical characteristic or attribute associated with the population being studied
Variable
Constant
has a fixed numerical value
Qualitative
variables that are classified according to some attributes of categories
Qualitative data
described by words and letters
2 subgroups of qualitative data
- Dichotomic
2. Polynomic
Dichotomic
For of word with only two options
Polynomic
form of word with more than two options
Quantitaive
data from observations that are measured on numerical scale
Quantitative data
described using numbers
What are the two subgroups of quantitative data
- Discrete
2. Continuous
What are the two subgroups of quantitative data
- Discrete
2. Continuous
Discrete
result of counting
Continuous
result of measuring
What are the four numerical scale of measurement
- Nominal
- Ordinal
- Interval
- Ratio
Nominal Scale of Measurement
are categories in no logical order and have no particular relationship
Ordinal scale of measurement
categories in which order is implied. Values in one category are largen or smaller than values in other categories
Interval scale of measurement
a set of numerical measurements in which distance between numbers is of a known constant size. There is no absolute zero in this scale
Ratio
consists of numerical measurements where distance between numbers is of a known constant size. there is an absolute zero in this scale
What are the measures of the central tendency
- Mean
- Median
- Mode
Median
midpoint of an array of observations
Mean
Adding all the items or the observations and dividing the sum by the total number of observations
Mode
the observation that appears the most number of times in a distribution
