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Statistics by: Alan Cortina - Coggle Diagram
Statistics by: Alan Cortina
Methods of collecting data
Interview method
:
-Direct method: researcher personally interview the respondent.
-Indirect method: the researcher uses a telephone to interview the respondent.
2.
Questionnaire method
: Is a list of well-plannes questions written on paper, which can be either personally administered or mailed by the researcher to the respondent.
Observation method:
The researcher observes the subject of the study which may be an individual, a group, or any unit of interest
Registration method
: Eamples of data gathered using this method are those obtained from National Statistcs Office, Land Transportation, Department of Education, and other government agencies.
Mechanical Devices
: The devices can be used when gathering data for social and educational researches are the cera, projectator, tape recorder, etc. In chemical, biological and medical researches, the common devices are x-ray machine, CT scan, microscope, etc. In astronomy and atmospheric researches, the telescopes, barometer, radar machine, computer, etc.
Sampling techniques
1.
Random sampling
: selects a sample using the concept of the lottery method.
2.
Systematic sample
: Choose a starting value at random. Then choos every kth member of the population.
Stratified sample
: Selects a sample when the population is segmented into groups or sections called stratifications or strata.
4.
Cluster sample
: Divide the population into groups (clusters) and select all of the members in one or more but not all, of the clusters.
Data classification
Primary data
: They refer to the information which is directly gathered from respondents or which is based on direct or firsthand experience. Example: diary
Secondary data
: They refer to the information which is taken from published or unpublished data gathered by other individuals or agencies. Example: Magazine, books.
Types of variables
Qualitative varuable: Consists of attributes, labels, or nonnumerical entries
Quantitative variables : Numerical measurements or counts.
Continuous data: numerical responses that arise from a measurement process. ex: 1.234in, 2.8cm
Discrete data: These are numerical responses that arise from counting process. Ex Number of children in a community.
Levels of measurement
Nominal level: for qualitative data only, categorized using names, labels or qualities. No mathematical computations can be made.
2 Ordinal level: qualitative and quantitative data, data can be arranged in order, differences between data entries is not meaningful.
Interval level: Quantitative data, data can ordered, differences between data entries is meaningful, zero represents a position in a scalel (not an inherent zero-zero does note imply none)
Ratio level: Similar to interval level, zero entry is an inherent zero (implies none), a ratio of two data values can be formed, one data value can be expressed as a multiple of another.
Data
Consists of information coming from observations, counts, measurements.
Data sets
Population
:The collection of all outcomes, responses, measurements, or counts that are of interest.
Parameter: a number that describes a population characteristic
For example: Average age of all people in the U.S.
Samples
: A subset of the population.
Statistic: A number that describes a sample characteristic. For ex: Average age of people from a sample of three states.
Applied mathematics that deals with collection, organization, presentation, analysis, and interpetation of numerical data in order to make decisions.
Descriptive statistics
: Involves organizing , summarizing, and displayig data. eg: Tables, charts, averages.
Inferential statistic
: Involves using sample data to draw conclusions about a population