3.3 Graphical Method
Presenting data using the graphical method facilitates the easy comparison and interpretation of data without having to go through numerical data.
Types of Charts:
Bar Chart - represented by either vertical or horizontal rectangles whose bases represent the class intervals and whose heights represent frequencies
Examples: {Click on image to see full-sized chart.}
Data can also be presented by using tables. Important features and significant values are easily observed when data are presented in a tabular form. Moreover, comparisons are also easily made.
Parts of a Table:
Example:
| Subject | Number of Books |
|---|---|
| Math | |
| Science | |
| English | |
| Filipino | |
| AP |
Source: PWC Library ← Souce Note
Row classifiers: Math, Science, English, Filipino, AP
The TEXTUAL METHOD is used when ungoruped data is presented in a paragraph form. The paragraph or text presents (usually through enumeration) the important characteristics of the data. It also gives emphasis to significant figures (or values) and important features of the data such as trends, irregularities and extreme values, if any.
In order to see or observe the significant characteristics of a data set, it must be presented in an organized and systematic way. There are three ways to present data: textual, tabular, and graphical.
There are two ways of classifying data: grouped and ungrouped.
Ungrouped data - not organized; if arranged, could only be from highest to lowest or lowest to highest
Grouped data - organized and arranged into different classes or categories
Example:
A simple list of the birthdays of the students of a section is ungrouped data even if it arranged from first to last or last to first. But if it is listed by month, it is grouped data.
A SAMPLING TECHNIQUE is a procedure used to determine the indiciduals or members of a sample. It may be a probability or non-probability sampling technique.
Probability Sampling - each member ir element of the population has an equal chance of being selected as members of the sample
In research, the entire population is seldom used because of the cost and time involved. Most researches use only a small representative of a population called the sample. The sample is used to know and/or describe the characteristics of a population.
COLLECTING DATA is the first step in conducting a research or study. It may be gathered from primary or secondary sources.
Primary Sources - statistical data from government institutions, business agencies, civil society organizations, first-hand surveys and interviews
Secondary Sources - books, encyclopedia, journals, magazines, research or studies by other people
SUMMATION NOTATION or SUMMATION (Σ) is the most common symbol used in statistics.
In statistics, variables are represented by using capital letters.
Example:
If we want to represent the age of 40 students in a class, the age of the first student is represented by X1, the age of the second student is X2, the age of the third student is X3, and so on until X40. The sum of the ages can be expressed in this way:
Nominal Scale - most primitive level of mesurement; used when we want to distinguish one object from nanother but the amount of difference cannot be determined
Examples:
Gender and nationality are in the nominal scale.
Alive or dead (fish) are also in the nominal scale.
Ordinal Scale - data are arranged in some specified order or rank; we can say that one is better or greater than the other; cannot tell how much more or how much less
Examples:
order of children in a family;
order of 10 fish according to their length (1st, 2nd, 3rd, etc)
Interval Scale - the amount of difference between two data is known or specified
Example:
If John is 35 years old and Ben is only 6 years old, we can say that John is 29 years older than Ben.
Ratio Scale - similar to the interval scale, but always starts from an absolute or zero point; there is always the presence of measure
Example:
If John is 75 kg and Ben is only 25 kg, then we can say that John is three times heavier than Ben or that Ben is three times lighter than John.
Population - large collection fo objects persons, places or things
Examples:
All the residents of the Philippines is considered a population.
All the fish in a lake is considered a population.
Samples - small portion or part of a population; also a subgroup, subset, or representative of a population.
Examples:
10,000 Filipinos is a sample of the Philippine population.
175 fish in a lake is a sample of the fish population in the lake.
Parameter - any numerical or nominal characteristic of a population
Examples:
The age of the selected Filipinos (or even of the whole population) is a parameter.
The length of the fish is a parameter.