describe the major statistical techniques for organising the data with suitable example and diagram
Answers
Answered by
0
There are a wide variety of ways to summarize, organize, and present data. Most of the common methods, such as stem-and-leaf diagrams, frequency distributions, histograms, bar, and other graphs, will be summarized here, along with the usual conventions and terms for each.
Coding Data
It is common practice to code data by assigning numerical values to nonnumeric measurements. An example might be to code gender as 1's and 2's instead of "male" and "female". The choice of 1 for male and 2 for female is rather arbitrary, but might correspond to the number of X-chromosomes in each somatic cell. One reason for data coding is to conserve storage space which historically was at a premium. (A keypunch card only held 80 bytes. Flat it is about the size of of a CD-ROM, rolled up it is about the size of a thumb drive, either of which easily holds half a gigabyte or so!) Another reason is that there are no upper and lower case [arabic] numbers. A computer may not register "male" as equal to "Male" or even "MALE". As computer storage costs have declined and computer software sophistication has increased, this practice may be in decline, but the concept remains important.
Data must somehow be entered into a computer before it can be analyzed. Optical scan sheets might be used or the data keyed in using a [micro]computer. Most statistical packages can import data, but comma separated, quote delineated, or fixed length fields are expected.
Various file editors can be utilized but the concept of a data record akin to a punch card is becoming an archaic concept. If one were to use a word processor, "hard returns" may be necessary and a fixed pitch font might help determine that the data is aligned into the proper columns. These programs generally allow the export of "flat ASCII" or ".txt" type files. (The alternative to ASCII (EBCDIC) is becoming a historic footnote as well.)
Spreadsheet programs have become a common way to enter data. As stated in the syllabus, however, they do not replace statistical packages for analyzing data. Generally there are no statisticians employed in the creation of spreadsheet programs, there is no warranty, implied nor expressed, regarding the validity of its statistical output, so time is probably better spent otherwise!
Exploratory Data Analysis
A recent trend in statistics has been the use of exploratory data analysis. It is a fundamentally different approach to analyzing data. Historically, statistics were used to confirm final conclusions about data. Some very important assumptions were made, calculations were complex, and graphs often unnecessary. The modern emphasis has been more on exploring data, trying to simplify the way the data are described, and gain deeper insights into its nature. Few assumptions are made, the calculations are simple, as are the graphs. The next two plot types (stem-and-leaf and box-and-whiskers) are modern in their approach.
Stem-and-Leaf Diagrams
John Tukey in the late 1970s developed many techniques for Exploratory Data Analysis, one of which, the stem-and-leaf diagram, has become especially popular. A stem-and-leaf diagram has the advantage of retaining the data in its original form, but providing a visual representation. Illustrated below is the U.S. Presidential Inauguration age data. In this case, thestem, the tens portion of the president's age, is given on the left, and the leaf, the units portion of the president's age, is given on the right.
4|236678995|01111122444445555666777786|0111244589
Please note that the separation line should be continuous, but time constraints limited accomplishing that feat. The following rules should be observed when constructing stem-and-leaf diagrams.
The leaves on the right should be in increasing (or decreasing) order, left to right.No commas should appear on the right.No horizontal lines should appear.If the stem/leaf break occurs at a decimal point, put the decimal point to the left with the stem.If the leaf is double or triple digit, etc., leave a [half] space between each entry.There should be at least five but no more than twenty rows.If a range is used for the stem, an asterisk (*) may be used to separate the corresponding leaves.Reformatting the above with more rows (called by some books splitting the stem) emphasizes even more its normally distributed nature. Notice how the stem-and-leaf diagram is also somewhat like a histogram, but turned on its side. Normally, data are rounded before being put into such a diagram, but ages, for whatever reason, usually get truncated! Many common statistical packages will generate stem-and-leaf diagrams.
4|234|6678995|01111122444445|5555666777786|01112446|589
Coding Data
It is common practice to code data by assigning numerical values to nonnumeric measurements. An example might be to code gender as 1's and 2's instead of "male" and "female". The choice of 1 for male and 2 for female is rather arbitrary, but might correspond to the number of X-chromosomes in each somatic cell. One reason for data coding is to conserve storage space which historically was at a premium. (A keypunch card only held 80 bytes. Flat it is about the size of of a CD-ROM, rolled up it is about the size of a thumb drive, either of which easily holds half a gigabyte or so!) Another reason is that there are no upper and lower case [arabic] numbers. A computer may not register "male" as equal to "Male" or even "MALE". As computer storage costs have declined and computer software sophistication has increased, this practice may be in decline, but the concept remains important.
Data must somehow be entered into a computer before it can be analyzed. Optical scan sheets might be used or the data keyed in using a [micro]computer. Most statistical packages can import data, but comma separated, quote delineated, or fixed length fields are expected.
Various file editors can be utilized but the concept of a data record akin to a punch card is becoming an archaic concept. If one were to use a word processor, "hard returns" may be necessary and a fixed pitch font might help determine that the data is aligned into the proper columns. These programs generally allow the export of "flat ASCII" or ".txt" type files. (The alternative to ASCII (EBCDIC) is becoming a historic footnote as well.)
Spreadsheet programs have become a common way to enter data. As stated in the syllabus, however, they do not replace statistical packages for analyzing data. Generally there are no statisticians employed in the creation of spreadsheet programs, there is no warranty, implied nor expressed, regarding the validity of its statistical output, so time is probably better spent otherwise!
Exploratory Data Analysis
A recent trend in statistics has been the use of exploratory data analysis. It is a fundamentally different approach to analyzing data. Historically, statistics were used to confirm final conclusions about data. Some very important assumptions were made, calculations were complex, and graphs often unnecessary. The modern emphasis has been more on exploring data, trying to simplify the way the data are described, and gain deeper insights into its nature. Few assumptions are made, the calculations are simple, as are the graphs. The next two plot types (stem-and-leaf and box-and-whiskers) are modern in their approach.
Stem-and-Leaf Diagrams
John Tukey in the late 1970s developed many techniques for Exploratory Data Analysis, one of which, the stem-and-leaf diagram, has become especially popular. A stem-and-leaf diagram has the advantage of retaining the data in its original form, but providing a visual representation. Illustrated below is the U.S. Presidential Inauguration age data. In this case, thestem, the tens portion of the president's age, is given on the left, and the leaf, the units portion of the president's age, is given on the right.
4|236678995|01111122444445555666777786|0111244589
Please note that the separation line should be continuous, but time constraints limited accomplishing that feat. The following rules should be observed when constructing stem-and-leaf diagrams.
The leaves on the right should be in increasing (or decreasing) order, left to right.No commas should appear on the right.No horizontal lines should appear.If the stem/leaf break occurs at a decimal point, put the decimal point to the left with the stem.If the leaf is double or triple digit, etc., leave a [half] space between each entry.There should be at least five but no more than twenty rows.If a range is used for the stem, an asterisk (*) may be used to separate the corresponding leaves.Reformatting the above with more rows (called by some books splitting the stem) emphasizes even more its normally distributed nature. Notice how the stem-and-leaf diagram is also somewhat like a histogram, but turned on its side. Normally, data are rounded before being put into such a diagram, but ages, for whatever reason, usually get truncated! Many common statistical packages will generate stem-and-leaf diagrams.
4|234|6678995|01111122444445|5555666777786|01112446|589
Answered by
1
Tabulation is one of the statistical methods of organising the data, the data is simply paraphrased and shortened to enable it the minimal size of the table, the tabulation method is a very suitable technique which makes it possible for one to proof read the statics using the very limited data and time frame so as to save on the time taken to accomplish the deal.
Similar questions