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SKILL.md
IPEDS Data Source Reference
IPEDS (Integrated Postsecondary Education Data System) — the primary federal data system for ~6,500 U.S. postsecondary institutions, comprising 12+ annual survey components: enrollment, completions, graduation rates, finance, financial aid, admissions, human resources, and institutional characteristics (1980-present, varies by component). Use when analyzing postsecondary enrollment, degree completions by CIP code, institutional finances, or admissions data. Graduation rates track first-time full-time students only (150% cohort). Cross-sector finance comparisons require care due to GASB vs. FASB accounting.
Comprehensive guide to understanding and using IPEDS data correctly. IPEDS is the most widely used source for postsecondary education data but has significant complexities — including sector-specific accounting standards, cohort-limited graduation rates, and integer-encoded categorical variables — that users must understand.
CRITICAL: Value Encoding
This document describes Education Data Portal integer encodings, which differ from NCES raw file string codes. The Portal converts categorical variables to integers for consistency across sources.
Context
Race White
Race Black
Sex Male
Sector Public 4-yr
Portal (integers)
1
2
1
1
NCES raw files
EFFY_WHITE
EFFY_BKAA
M
varies
Always verify codes against Portal codebooks (available alongside each dataset in the Portal mirrors).
What is IPEDS?
IPEDS (Integrated Postsecondary Education Data System) is a system of 12+ interrelated survey components:
Administered by: National Center for Education Statistics (NCES)
Coverage: ~6,500 Title IV-participating postsecondary institutions
Frequency: Annual collection in three periods (Fall, Winter, Spring)
Mandate: Required for Title IV federal student aid participation
Available years: 1980-present (varies by component)
Available through: Education Data Portal mirrors (32 datasets covering most survey components; some variables not mirrored — see Data Access section)
Reference File Structure
File
Purpose
When to Read
survey-components.md
All 12+ IPEDS surveys with collection periods
Understanding data structure
graduation-rates.md
CRITICAL GRS limitations and who is tracked
Any graduation rate analysis
enrollment-data.md
Fall vs 12-month, FTE calculations
Enrollment comparisons
finance-data.md
GASB vs FASB accounting standards
Cross-sector finance analysis
financial-aid.md
Net price, aid types, populations
Aid and cost analysis
institution-identifiers.md
UNITID, OPEID, mergers, closures
Data linking and longitudinal work
completions-data.md
Degrees awarded, CIP codes
Completions and outcomes
data-quality.md
Known issues, sector comparisons
Quality assurance
Decision Trees
What data am I working with?
Working with IPEDS data?
├─ Graduation rates → ./references/graduation-rates.md (READ FIRST!)
├─ Enrollment counts → ./references/enrollment-data.md
├─ Finance/revenue/expenses → ./references/finance-data.md
├─ Financial aid/net price → ./references/financial-aid.md
├─ Degrees/completions → ./references/completions-data.md
├─ Institutional info → ./references/survey-components.md (IC section)
├─ Human resources/salaries → ./references/survey-components.md (HR section)
└─ Linking to other data → ./references/institution-identifiers.md
Is my analysis valid?
Cross-sector comparison?
├─ Comparing grad rates across sectors
│ └─ CAUTION: Different populations → ./references/graduation-rates.md
├─ Comparing finances across sectors
│ └─ CAUTION: GASB vs FASB → ./references/finance-data.md
├─ Comparing net price across sectors
│ └─ CAUTION: Aid populations differ → ./references/financial-aid.md
└─ Time series analysis
└─ Check for institutional changes → ./references/institution-identifiers.md
Finding specific variables?
Need variable definitions?
├─ Survey component overview → ./references/survey-components.md
├─ Graduation cohort definitions → ./references/graduation-rates.md
├─ Enrollment level/status → ./references/enrollment-data.md
├─ Revenue/expense categories → ./references/finance-data.md
├─ Aid types and populations → ./references/financial-aid.md
└─ CIP codes for programs → ./references/completions-data.md
Quick Reference: Survey Components
Component
Abbrev
Collection
Key Content
Institutional Characteristics
IC
Fall
Directory, tuition, mission
12-Month Enrollment
E12
Fall
Unduplicated headcount, FTE
Completions
C
Fall
Degrees by CIP, demographics
Cost
CST
Fall/Winter
Cost of attendance, net price
Admissions
ADM
Winter
Applications, admits, enrollees
Student Financial Aid
SFA
Winter
Aid counts and amounts
Graduation Rates
GR
Winter
150% completion rates
Graduation Rates 200%
GR200
Winter
200% completion rates
Outcome Measures
OM
Winter
Part-time and transfer outcomes
Fall Enrollment
EF
Spring
Point-in-time enrollment
Finance
F
Spring
Revenue, expenses, assets
Human Resources
HR
Spring
Employees, salaries
Academic Libraries
AL
Spring
Library resources (biennial)
Key Identifiers
ID
Format
Level
Example
Notes
unitid
6-digit integer
Institution
100654
Unique, persistent across years; changes on merger
opeid
8-digit string
Institution (Title IV)
00100200
Links to FSA/NSLDS; shared across branches
Institution Type Codes
Variable
Values
Meaning
inst_control
1
Public
2
Private nonprofit
3
Private for-profit
-1
Missing/not reported
institution_level
1
Less than 2-year
2
2-year (at least 2 but less than 4)
4
4-year or above
-1
Missing/not reported
sector
0
Administrative unit
1
Public, 4-year or above
2
Private not-for-profit, 4-year or above
3
Private for-profit, 4-year or above
4
Public, 2-year
5
Private not-for-profit, 2-year
6
Private for-profit, 2-year
7
Public, less-than 2-year
8
Private not-for-profit, less-than 2-year
9
Private for-profit, less-than 2-year
-1
Sector unknown (not active)
hbcu
1
Historically Black College/University
0
Not HBCU
-1
Missing/not reported
tribal_college
1
Tribal College
0
Not Tribal College
-1
Missing/not reported
degree_granting
1
Degree-granting
0
Non-degree-granting
Note: There is no code 3 for institution_level. The Portal uses codes 1, 2, 4 (not 1, 2, 3).
inst_size Categories
Code
Meaning
1
Under 1,000
2
1,000 - 4,999
3
5,000 - 9,999
4
10,000 - 19,999
5
20,000 and above
Note:inst_size is a category code (1-5), not an actual enrollment count.
Race/Ethnicity Codes (Portal Integer Encoding)
Code
Category
Notes
1
White
Single race, non-Hispanic
2
Black
Single race, non-Hispanic
3
Hispanic
Any race
4
Asian
Single race, non-Hispanic
5
American Indian/Alaska Native
Single race, non-Hispanic
6
Native Hawaiian/Pacific Islander
Single race, non-Hispanic
7
Two or more races
Multiple races selected, non-Hispanic
8
Nonresident alien
International students
9
Unknown
Race/ethnicity unknown
20
Other
Other race/ethnicity
99
Total
All races combined
-1
Missing/not reported
-2
Not applicable
-3
Suppressed
Privacy protection
Historical note: Prior to 2010, Asian included Pacific Islanders (code 6 did not exist), and "Two or more races" (code 7) was not collected.
Sex Codes (Portal Integer Encoding)
Code
Category
1
Male
2
Female
3
Nonbinary/Another gender
4
Unknown/Prefer not to say
9
Unknown
99
Total
-1
Missing/not reported
-2
Not applicable
-3
Suppressed
Note: Codes 3 and 4 are recent additions for non-binary gender reporting. Historical data may only have codes 1, 2, and 99. The exact meaning of codes 3 vs 4 may vary by endpoint — check the specific codebook.
Missing Data Codes
Code
Meaning
When Used
-1
Missing/not reported
Data not submitted by institution
-2
Not applicable
Item doesn't apply to this institution type
-3
Suppressed
Data suppressed for privacy
null
Not available
Field not collected for this survey year
Year Field Meanings
Data Type
Year Field Meaning
Institutional characteristics
As of fall of indicated year
Fall enrollment
As of fall census date
12-month enrollment
July 1 to June 30 academic year
Completions
Awarded during academic year
Graduation rates
Cohort entered in indicated year
Finance
Fiscal year ending in indicated year
Student financial aid
For indicated academic year
Data Access
Datasets for IPEDS are available via the mirror system. See datasets-reference.md for canonical paths, mirrors.yaml for mirror configuration, and fetch-patterns.md for fetch code patterns.
Truth Hierarchy: When interpreting variable values, apply this priority:
Actual data file (what you observe in the parquet/CSV) — this IS the truth
Live codebook (.xls in mirror) — authoritative documentation, may lag
This skill documentation — convenient summary, may drift from codebook
If this documentation contradicts the codebook, trust the codebook. If the codebook contradicts observed data, trust the data and investigate.
Filtering
import polars as pl
# Admissions totals: filter to sex=99 for institution-level totals
# WRONG - includes duplicates (~26K rows with multiple sex values per institution)
df = pl.read_parquet("data/raw/admissions.parquet")
# CORRECT - one row per institution-year (~8K rows)
df_totals = df.filter(pl.col("sex") == 99)
# Calculate admission rate (not provided directly)
df = df.with_columns(
(pl.col("number_admitted") / pl.col("number_applied") * 100).alias("admit_rate")
)
# Filter to active, degree-granting, 4-year public institutions
df = df.filter(
(pl.col("sector") == 1) &
(pl.col("degree_granting") == 1)
)
Data Availability & Lag Times
IPEDS data becomes available with significant lag. Always verify year availability before committing to a year range.
Survey Component
Typical Lag
Latest Available (as of Jan 2026)
Directory
~1 year
2023
Admissions-Enrollment
~2 years
2022
Fall Enrollment
~2-3 years
2022
Completions
~2 years
2022
Finance
~4+ years
2017 (see warning below)
Graduation Rates
~2-3 years
2022
CRITICAL: IPEDS Finance Data Cutoff. As of January 2026, IPEDS Finance data is only available through 2017 in the Portal mirrors. This affects endowment values (endowment_end), revenue/expense data, and any financial ratios. Options: (1) limit analysis to available years, (2) use NCCS 990 data for private institutions as an alternative, or (3) forward-fill with a documented caveat and indicator column.
Variable Name Mappings
The Portal uses different names than NCES raw file documentation. The table below lists commonly confused mappings:
NCES Raw File Name
Actual Portal Name
Notes
INSTNM
inst_name
Institution name
STABBR
state_abbr
State abbreviation
CONTROL
inst_control
Institutional control
ICLEVEL
institution_level
Level of institution
DEGGRANT
degree_granting
Degree-granting status
CYACTIVE
currently_active_ipeds
Currently active flag
DEATHYR
year_deleted
Year institution closed
APPLCN
number_applied
Total applicants
ADMSSN
number_admitted
Total admitted
EFTOTLT
enrollment_fall
Fall enrollment (in fall-enrollment-race dataset)
various GR*
completion_rate_150pct, completers_150pct, etc.
Grad rate variables
Note: Portal variable names are always lowercase with underscores. NCES documentation often uses UPPERCASE or CamelCase. When in doubt, fetch a sample of the actual data and inspect its column names.
Enrollment Dataset Clarification
IPEDS has multiple enrollment-related datasets in the Portal:
Note: The fall-enrollment-race yearly dataset provides the most granular enrollment data, disaggregated by multiple dimensions. For institution-level totals, filter to race == 99, sex == 99, ftpt == 99, level_of_study == 99.
Common Pitfalls
Pitfall
Issue
Solution
Using string codes
Portal uses integer encodings, not NCES string codes
Always verify against Portal codebooks; see encoding table above
Use Outcome Measures (OM) for part-time/transfer data; note limitations
Cross-sector finance comparison
Public (GASB) and private (FASB) use different accounting standards
Compare within sector only; see ./references/finance-data.md for crosswalk
Net price for all students
Net price covers only first-time, full-time students who received Title IV aid
Document population limitation; excludes full-pay students
Admissions without sex filter
Admissions data disaggregated by sex — unfiltered data has duplicates
Filter to sex == 99 for institution totals
No institution_level 3
Codes are 1, 2, 4 — not sequential 1, 2, 3
Use exact codes: 1=less-than-2yr, 2=2yr, 4=4yr+
Ignoring mergers/closures
Institutions merge, close, or change sector over time
Check currently_active_ipeds and year_deleted; track UNITID changes; see ./references/institution-identifiers.md
inst_size as enrollment
inst_size is a 1-5 category code, not an enrollment count
Use enrollment endpoints for actual counts
Distance education variables missing
efdeexc, efdesom, efdenom are not in Portal mirror datasets
Use the NCES IPEDS Data Center directly for distance education enrollment
GRS duplicate rows per institution
Graduation rates data has multiple rows per unitid within the same subcohort/year, differing in cohort_rev and count columns
Filter to target subcohort first (e.g., subcohort == 2 for bachelor's-seeking at 4-yr), then deduplicate: sort by completion_rate_150pct descending (nulls last), then unique(subset=["unitid"], keep="first")
open_public is not open admissions
open_public (from openpubl) means "open to the general public" (i.e., a currently operating institution) — Harvard has open_public=1. The actual open-admissions policy variable (OPENADMP) is not available in the Portal mirror
Do not use open_public to identify open-admissions institutions. Use admissions data (admit rate near 100%) as a proxy, or access OPENADMP via the IPEDS API directly
SFA type_of_aid=9 is all grants, not Pell
type_of_aid=9 in sfa_grants_and_net_price captures ALL grant/scholarship recipients (Pell + institutional + state/local). The median ratio to total students is ~0.98 — nearly universal. This dramatically overestimates "Pell share" if used as a Pell proxy
For Pell-specific data, use FSA (pre-2020) or College Scorecard bulk download. SFA type_of_aid=9 is appropriate for total grant aid analysis but not for Pell isolation
Critical Limitations
Graduation Rates (GRS)
CRITICAL: IPEDS graduation rates track ONLY first-time, full-time, fall-entering students.
Excluded Population
Approximate % of Undergrads
Transfer students
~40%
Part-time students
~40%
Spring/summer starts
Varies
Students who transfer OUT
Counted as non-completers
At community colleges, IPEDS grad rates may represent <25% of students.
See ./references/graduation-rates.md for complete details.
Finance Data
CRITICAL: Public and private institutions use different accounting standards.
Standard
Institution Type
Comparison
GASB
Public
Compare within sector only
FASB
Private nonprofit
Different from GASB
FASB
Private for-profit
Different revenue treatment
See ./references/finance-data.md for crosswalk guidance.
Net Price
Net price is calculated ONLY for:
First-time, full-time students
Who received Title IV aid
Excludes full-pay students
See ./references/financial-aid.md for details.
Data Quality Checklist
import polars as pl
def ipeds_quality_check(df):
"""Basic IPEDS data quality checks using Portal variable names."""
issues = []
# Check graduation rates — Portal stores as 0-1 proportions (not 0-100)
# See education-data-context skill > Rate and Proportion Normalization
if "completion_rate_150pct" in df.columns:
bad = df.filter(
(pl.col("completion_rate_150pct") > 1.0) |
(pl.col("completion_rate_150pct") < 0)
)
if bad.height > 0:
issues.append(f"Invalid grad rates: {bad.height} rows")
# Check for non-active institutions (directory dataset)
if "currently_active_ipeds" in df.columns:
inactive = df.filter(pl.col("currently_active_ipeds") != 1)
if inactive.height > 0:
issues.append(f"Non-active institutions: {inactive.height}")
# Check sector consistency
if "inst_control" in df.columns:
invalid = df.filter(
~pl.col("inst_control").is_in([1, 2, 3, -1])
)
if invalid.height > 0:
issues.append(f"Invalid control codes: {invalid.height}")
return issues
