preFinals Math In Modern World Flashcards
are raw information or facts that become useful information when organized in a meaningful way. It could be of qualitative and quantitative nature.
Data
is concerned with “looking after” and processing data
Data Management
Data management involves the following: (there are 4 items)
• Looking after field data sheets
• Checking and correcting the raw data
• Preparing data for analysis
• Documenting and archiving the data and meta-data
Importance of Data Management
(there are 3 items)
•Ensures that data for analysis are of high quality so that conclusions are correct
• Good data management allows further use of the data in the future and enables efficient integration of
results with other studies.
• Good data management leads to improved processing efficiency, improved data quality, and improved meaningfulness of the data.
Methods of Data Collection
(4 items)
Census
Sample survey
Experiment
Observation study
this is the procedure of systematically acquiring and recording information about all members of a given population. Researchers rarely survey the entire population for two (2) reasons: the cost is too high and the population is dynamic in that the individuals making up the population may change over time.
Census
sampling is a selection of a subset within a population, to yield some knowledge about
the population of concern. The three main advantages of sampling are that (i) the cost is lower, (ii) data
collection is faster, and (iii) since the data set is smaller, it is possible to improve the accuracy and quality
of the data.
Sample survey
this is performed when there are some controlled variables (like certain treatment in medicine) and the intention is to study their effect on other observed variables (like health of patients). One of the main requirements to experiments is the possibility of replication.
Experiment
this is appropriate when there are no controlled variables and replication is impossible. This type of study typically uses a survey. An example is one that explores the correlation
between smoking and lung cancer. In this case, the researchers would collect observations of both smokers and non-smokers and then look for the number of cases of lung cancer in each group.
Observation study
Planning and Conducting Surveys
1. Characteristics of a well-designed and well-conducted survey
a. ?
b. ?
c. ?
d. ?
- A good survey must be representative of the population.
-
To use the probabilistic results, it always incorporates a chance, such as a random number generator.
Often we don’t have a complete listing of the population, so we have to be careful about exactly how
we are applying “chance”. Even when the frame is correctly specified, the subjects may choose not to
respond or may not be able to respond. - The wording of the question must be neutral; subjects give different answers depending on the phrasing.
-
Possible sources of errors and biases should be controlled. The population of concern as a whole may not be available for a survey. Its subset of items possible to measure is called a sampling frame (from
which the sample will be selected). The plan of the survey should specify a sampling method, determine
the sample size and steps for implementing the sampling plan, and sampling and data collecting.
2 types of sampling method
Non-probability sampling
Probability sampling
is any sampling method where some elements of the population have no
chance of selection or where the probability of selection can’t be accurately determined.
Non-probability sampling
it is possible to both determine which sampling units belong to which sample and the probability that each sample will be selected.
Probability sampling
One example of nonprobability sampling is** 1. ___________ **sampling (customers in a supermarket are
asked questions). Another is 2. _____ sampling, when judgment is used to select the subjects based on
specified proportions.
- convenience sampling
- quota sampling
The following sampling methods are example of probability sampling:
(There are 5 of them)
Simple Random Sampling (SRS)
Systematic sampling
Stratified sampling
Cluster sampling
Matched random sampling