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| = Datetime = | = SPSS Data Types = |
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| == A warning about data input == | SPSS exposes numeric and string data types. |
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| SPSS tries to be clever about reading data. | Certain specialized forms of data are handled by formats that impact visualization and export, not storage. The primary example of this is date and time data. |
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| Under the format `TIME`, all of these are read in as `"01:02"`, even though the format is a minimum of 5-wide: * `"1:2"` * `"01 2"` * `"01:02"` |
<<TableOfContents>> |
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| Under the format `DATE`, all of these are read in as `"28-OCT-90"`: * `"28-OCT-90"` * `"28/10/1990"` * `"28.OCT.90"` * `"28 October, 1990"` |
---- == Numeric Data == '''Numeric''' data is stored as double-precision floating point. Data formats adjust the visualized/exported representation of a data point, often only truncating the value. Adjusting these data formats does not destroy precision. Given the literal value 123.45... ||'''General Format''' ||'''Format''' ||'''Representation''' || ||Fw ||F8 ||123 || ||Fw.d ||F8.1 ||123.4 || ||Nw ||N8 ||00000123 || ||Nw.d ||N8.1 ||000123.4 || See [[SPSS/NumericFunctions|here]] for the built-in library of numeric functions. |
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| == Datetime formats == | === Date and Time Formats === |
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| ||'''Format''' ||'''Appears as...''' ||'''Note''' || ||DATETIME20 ||`dd-MMM-yyyy hh:mm:ss` ||`MMM` is as JAN, not 001|| ||DATETIME18 ||`dd-MMM-yyyy hh:mm` ||`MMM` is as JAN, not 001|| ||DATE11 ||`dd-MMM-yyyy` ||`MMM` is as JAN, not 001|| ||DATE7 ||`dd-MMM-yy` ||`MMM` is as JAN, not 001|| ||TIME8 ||`hh:mm:ss` || || ||TIME5 ||`hh:mm` || || ||ADATE10 ||`mm/dd/yyyy` || || ||ADATE8 ||`mm/dd/yy` || || ||EDATE10 ||`dd.mm.yyyy` || || ||EDATE8 ||`dd.mm.yy` || || |
'''Date''' data is stored as the number of seconds from midnight, October 14, 1582 to midnight on the specified date. '''Datetime''' data is stored as the number of seconds to the specified time on the specified date. '''Time''' data is stored as the number of seconds. This ''can'' be imagined as the number of seconds from midnight to the specified time, but that is not a ''necessary'' construct. Keep in mind that 1 day = 60 (seconds) * 60 (minutes) * 24 (hours) = 86400 seconds. ||'''Format''' ||'''Representation''' || ||`DATETIME20` ||`dd-MMM-yyyy hh:mm:ss` || ||`DATETIME17` ||`dd-MMM-yyyy hh:mm` || ||`DATE11` ||`dd-MMM-yyyy` || ||`DATE9` ||`dd-MMM-yy` || ||`TIME8` ||`hh:mm:ss` || ||`TIME5` ||`hh:mm` || ||`ADATE10` ||`mm/dd/yyyy` || ||`EDATE10` ||`dd.mm.yyyy` || ||`SDATE10` ||`yyyy/mm/dd` || Note that `MMM` appears as `JAN`, not `001`. Note that `DATE11` and `DATE9` differ in the representation of years ''(4 and 2 digits respectively)''. The American, European, and Sortable date formats have a similar feature by swapping `[AES]DATE10` with `[AES]DATE8`. See [[SPSS/DateTimeFunctions|here]] for the built-in library of date and time functions. ---- |
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| ---- | == String Data == |
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| = Numerics = | '''String''' data is stored at a fixed length. This length is defined and adjusted through the format; `Aw` where `w` is the width. |
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| Formats only truncate the displayed value, or the value translated into data files. SPSS always retains data to original precision. Given 123.45... ||'''Format''' ||'''Using...''' ||'''Appears as...''' || ||Fw ||F8 ||123 || ||Fw.d ||F8.1 ||123.4 || ||Nw ||N8 ||00000123 || ||Nw.d ||N8.1 ||000123.4 || ---- = Strings = String variables are only formatted to a length. The format is specified as `AN` where `N` is the width. |
See [[SPSS/StringFunctions|here]] for the built-in library of string functions. |
SPSS Data Types
SPSS exposes numeric and string data types.
Certain specialized forms of data are handled by formats that impact visualization and export, not storage. The primary example of this is date and time data.
Numeric Data
Numeric data is stored as double-precision floating point.
Data formats adjust the visualized/exported representation of a data point, often only truncating the value. Adjusting these data formats does not destroy precision.
Given the literal value 123.45...
General Format |
Format |
Representation |
Fw |
F8 |
123 |
Fw.d |
F8.1 |
123.4 |
Nw |
N8 |
00000123 |
Nw.d |
N8.1 |
000123.4 |
See here for the built-in library of numeric functions.
Date and Time Formats
Date data is stored as the number of seconds from midnight, October 14, 1582 to midnight on the specified date.
Datetime data is stored as the number of seconds to the specified time on the specified date.
Time data is stored as the number of seconds. This can be imagined as the number of seconds from midnight to the specified time, but that is not a necessary construct.
Keep in mind that 1 day = 60 (seconds) * 60 (minutes) * 24 (hours) = 86400 seconds.
Format |
Representation |
DATETIME20 |
dd-MMM-yyyy hh:mm:ss |
DATETIME17 |
dd-MMM-yyyy hh:mm |
DATE11 |
dd-MMM-yyyy |
DATE9 |
dd-MMM-yy |
TIME8 |
hh:mm:ss |
TIME5 |
hh:mm |
ADATE10 |
mm/dd/yyyy |
EDATE10 |
dd.mm.yyyy |
SDATE10 |
yyyy/mm/dd |
Note that MMM appears as JAN, not 001.
Note that DATE11 and DATE9 differ in the representation of years (4 and 2 digits respectively). The American, European, and Sortable date formats have a similar feature by swapping [AES]DATE10 with [AES]DATE8.
See here for the built-in library of date and time functions.
String Data
String data is stored at a fixed length. This length is defined and adjusted through the format; Aw where w is the width.
See here for the built-in library of string functions.