Probstat

The

median is the midpoint of an array of numbers or observations.

mode is the score or observation that appears the most number of times in a

distribution. It is associated with nominal data

Primary data means the raw data that has only been obtained from the source and

has not gone through any kind of statistical treatment such as sorting and tabulation

Secondary data on the otherhand, are data that has already been obtained by others

can be categorized, tabulated and statistically handled

Sampling is a technique that enables

researchers to infer population information on the basis of results from a subset of the

population without having to examine each individual.

Simple Random Sampling

In this scenario, each person is chosen entirely by chance and each member of the

population has an equal chance, or likelihood, of being chosen

Systematic Random Sampling

Individuals are picked from the sampling frame at regular intervals. To ensure an

appropriate sample size, the intervals are chose

Stratified Random Sampling

The population is first divided into subgroups (or strata) in this system that all share

a common characteristic

Cluster Random Sampling

Subgroups of the population are used in a clustered survey as the sampling unit,

rather than individuals.

Convenience Sampling

Convenience sampling is perhaps the simplest sampling process, as participants are

chosen on the basis of availability and willingness to participate

Quota Sampling

Market analysts also make use of this method of sampling. A quota of subjects of a

specified sort to attempt to recruit is given to interviewers.

Purposive Sampling

Often known as selective, or subjective, sampling, when deciding who to ask to

participate, this approach relies on the researcher's judgment.

Frequency Distribution

A frequency distribution provides a visual representation for the distribution of

observations within a specific test as a statistical instrument.

Three forms of Data Presentation

Textual Form - The discussion of the presentation of data begins with the most raw

and ambiguous form which is the textual presentation.

Tabular Form - In an appealing, easy to read and structured way, a table enables the

representation of even large quantities of data.

Graphical Form - Diagrams play an important part in the presentation of statistical

results

Histogram

is a graphical data display using bars of various heights. Each

bar groups numbers into ranges in a histogram.

Frequency Polygon

A frequency polygon is a graphical type of information representation. It is

used to reflect the data's shape and to depict patterns.

OGIVE

are graphs used to estimate how many numbers in data lie below or

above a given variable or value.

Pie Chart

is a type of graph that displays a circular graph with details. In

each group, the pieces of the graph are equal to the fraction of the whole.

Descriptive statistics is a branch of statistics that includes the organisation, display

and description of data

nferential statistics is a branch of statistics which involves drawing conclusions

about the population on the basis of the information present in the sample taken from that

population.

Population pertains to the groups of people in a survey that are reflective of the

whole community you want to study

As access to the

entire population is rarely feasible, data is usually obtained from a sample or a group of the

population concerned

Sampling error

While samples should be representative of the population, sampling errors may have

a negative effect in certain situations.

Variable is a property or feature of a person, event or object that may have different

values or values (e.g. study time).

One where there is order is an

interval scale and the difference between two values is

important.

A ratio variable has all the characteristics of an interval variable and is also specifically

described as 0.0. There is "none of the variable" when the variable is equal to 0.0.