An Alternative Definition for IQR. In some texts, the interquartile range is defined differently. It is defined as the difference between the largest and smallest values in the middle 50% of a set of data. To compute an interquartile range using this definition, first remove observations from the lower quartile.
A hard drive is a device used to store data in a semipermanent state on your computer. Computer memory is a series of small packets of data called bits. Each bit is a 1 or a 0, and each bit is stored as a small magnetic charge on the hard drive. A read/write head moves over the hard drive to retrieve or rewrite the bits as needed.
Hard drive. A hard disk drive (sometimes abbreviated as Hard drive, HD, or HDD) is a non-volatile memory hardware device that permanently stores and retrieves data on a computer. A hard drive consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing. Internal hard disks reside in a drive bay, connect to the motherboard using an ATA, SCSI, or SATA cable, and are powered by a connection to the PSU (power supply unit).