# Presentation: 017595

## Differential Item Functioning of the English- and Spanish-AdministeredHINTS Psychological Distress Scale

**Chih-Hung Chang, Ph.D.**
**Feinberg School of Medicine**
**Northwestern University**

- HINTS DATA USER CONFERENCE
- January 20-21, 2005, St. Pete Beach, FL

## Objective

- To examine the extent to which the psychological distress items exhibiting differential item functioning (DIF) contribute to observed between-group differences  in reporting depression
- English- vs. Spanish-Administered CATI

## Participants

- A total of 6,369 respondents (18 years and older) from a national probability sample of general adult population were surveyed
- All 362 Spanish-administered participants included
- 362 English-administered participants randomly selected

## Sample Characteristics

|  |  | Spanish (n=362) | English (n=362) |
| --- | --- | --- | --- |
| Gender | Male | 155 | 177 |
| 	 | Female | 207 | 185 |
| Age | M ± s.d. | 40.2±16.1 | 49.4±18.2 |
| Race | Hispanic | 334 | 40 |
|  | Other | 28 | 322 |

## Measure

- Self-reported depression was measured by the 6-item Psychological Distress Scale (PDS; 0-12 not-depressed; 13-24 depressed)

## Psychological Distress Scale

- HS-2. During the past 30 days, how often did you feel [FEELING]?
- a. so sad that nothing could cheer you up
- b. nervous
- c. restless or fidgety
- d. hopeless
- e. that everything was an effort
- f. worthless

- 1=All of the time; 2=Most of the time; 3=Some of the time; 4=A little of the time; 5=None of the time

## Method

- Differential Item Functioning (DIF) analysis  based on multiple-group partial credit model was conducted
- DIF is said to occur when individuals with the same level of latent trait (e.g., depression) being measured but who come from different identifiable subgroups (e.g., English vs. Spanish) do not have the same probability of category endorsement

## ResultsSample Item Endorsement

## ResultsItem Characteristic Curve

## ResultsDifferential Item Functioning

|  | Slope | Location
(Spanish) | Location
(English) | p |
| --- | --- | --- | --- | --- |
| Excessively sad | 0.72 | 1.33 | 1.65 | 0.01 |
| Nervous | 0.61 | 1.40 | 1.23 | 0.21 |
| Restless | 0.74 | 1.22 | 0.97 | 0.03 |
| Hopeless | 1.58 | 1.40 | 1.62 | 0.04 |
| Everything is an effort | 0.42 | 1.06 | 1.01 | 0.75 |
| Worthless | 0.86 | 1.77 | 1.69 | 0.59 |

## ResultsSerious Psychological Distress

|  | Spanish (n=362) | English (n=362) |
| --- | --- | --- |
| No
(PDS score 0-12) | 284
(87.1%) | 324
(93.6% |
| Yes
(PDS score 13-24) | 42
(12.9%) | 22
(6.4%) |

## ResultsGeneral Health Status

|  | Spanish (n=362) | English (n=362) |
| --- | --- | --- |
| Excellent | 31 (9.2%) | 38 (10.9%) |
| Very Good | 35 (10.4%) | 107 (30.6%) |
| Good | 86 (25.5%) | 133 (38.0%) |
| Fair | 164 (48.7%) | 59 (16.9%) |
| Poor | 19 (5.6%) | 13 (3.7%) |

## Summary

- The response characteristic curves indicated that the five ordered response categories (ranging from “all of the time” to “none of the time”) worked as expected
- 3 items (“so sad that nothing could cheer you up”; “restless or fidgety”; “hopeless”) displayed DIF
- 12.9% Spanish-administered adults reported depressed (PDS score 13-24) and only 6.4% for those English-administered adults

## Conclusions

- Although Spanish-administered adults reported more depression, our findings suggest that the between-group comparison may be biased by DIF
- More research is needed to investigate the impact of different language version of other health-related measures, particularly those that use Likert-type response options

## Contact Information

- Chih-Hung Chang, Ph.D.
- Buehler Center on Aging
- Feinberg School of Medicine
- Northwestern University
- 750 N. Lake Shore Drive, Suite 601
- Chicago, IL 60611
- Tel: (312) 503-4354
- Fax: (312) 503-5868
- E-mail: chchang@northwestern.edu