Chapter 4 Questions Data & Information

What is lossless data compression?

• It is a form of data compression that reduces the data file size without any loss of data information. It allows the original file to be restored.

• It is a form of data compression that reduces the data file size with an acceptable loss of data information. It does not allow the original file to be restored.

• It is a form of data compression that reduces the data file size by removing non-essential data. When the file is restored it appears like the original file.

• It is a form of data compression that is only used for temporary data files. The file is reduced and stays compressed.

What is lossy data compression?

• It is a form of data compression that reduces the data file size without any loss of data information. It allows the original file to be restored.

• It is a form of data compression that reduces the data file size with an acceptable loss of data information. It does not allow the original file to be restored.

• It is a form of data compression that reduces the data file size by removing non-essential data. When the file is restored it appears like the original file.

• It is a form of data compression that is only used for temporary data files. The file is reduced and stays compressed.

How is it possible to reduce data file size for compression and then restore it to its original format without any loss of information?

• Clever algorithms are used that only remove non-essential "blank" data.

• The removed data is stored elsewhere on the Cloud and added later during restoring.

• Repetitive data, like a color on an image, can be stored with a formula.

• It is not really possible to restore 100%, but the data loss is not noticeable.

What is metadata?

• It is a name for the data that is lost during data compression.

• It is the data that has been analyzed and classified as significant.

• It is the name for data that is not compressed.

• It is data about data, such as file size, data format, creation date, etc.

Consider the adjacent image. This distorted image is an example of

• poor camera filming technique.

• pixilation.

• too much data compression.

• low resolution data storage.

Social media companies, like Facebook, lower picture quality of high resolution images before posting them on the Internet. Why is this an acceptable practice?

• Lower quality means smaller files and quicker transmission time.

• Lower quality means smaller files and less memory required for storing the image.

• Most people will not notice any difference. Social media does not require high resolution quality, such as is needed for printing large pictures or zooming.

• All of the above

A high resolution picture is taken of an eagle flying in the sky. Is this picture a good candidate for lossless data compression or should lossy data compression be used?

• Lossy data compression is fine, because the picture started with high resolution.

• This decision cannot be made without knowing the purpose of the image.

• This picture is a good candidate for lossless data compression. Much of the picture will include sky pixels of the same color that can be stored in a formula and restored to its original image quality.

• All still pictures should use lossless data compression. Only audio files and video files can manage lossy data compression well.

A school administration program stores information about students. The following student information is stored in the central database. Information can be retrieved by school employees based on their individual access rights.

- Student information about address, birthdate, gender and family

- Student medical records

- Attendance and tardies

- Student grades per course

- Student GPA & class standing

- School club membership

- School athletic team member

Which of the following requests cannot be determined using the school's database?

• School athlete with the highest GPA

• Students who need to take daily medicine at school

• Correlation between GPA and scholarship awarded

• Correlation between chronic illnesses and attendance