STAI

State Trait Anxiety Inventory

Measuring: Participant’s present level of anxiety/calmness.

Number of Items: 6

Item	Question Wording	TILDA Variable
1	I feel calm	COGstateanxiety1
2	I am tense	COGstateanxiety2
3	I feel upset	COGstateanxiety3
4	I am relaxed	COGstateanxiety4
5	I feel content	COGstateanxiety5
6	I am worried	COGstateanxiety6

Scoring method:

Scored on a 4-point Likert scale.

1 = Not at all

2 = Somewhat

3 = Moderately

4 = Very much

Responses to the six items were summed, resulting in an overall score

Positive items are reverse scored (calm, relaxed, content)
Multiple total score by 20/6 to generate an equivalent score to the standard 20-item equivalent.

Citation: Marteau, T. M., & Bekker, H. (1992). The development of a six-item short-form of the state scale of the Spielberger State-Trait Anxiety Inventory (STAI). British Journal of Clinical Psychology, 31, 301– 306

Spielberger, C. D. (1983). Manual for the State-Trait Anxiety Inventory (STAI). PaloAlto, CA: Consulting Psychologists Press.

Code

* Raw 6-item total score
egen COGstai6_total = rowtotal( ///
    COGstateanxiety1 ///
    COGstateanxiety2 ///
    COGstateanxiety3 ///
    COGstateanxiety4 ///
    COGstateanxiety5 ///
    COGstateanxiety6 ///
)

* Require all six items to be answered
egen COGstai6_missing = rowmiss( ///
    COGstateanxiety1 ///
    COGstateanxiety2 ///
    COGstateanxiety3 ///
    COGstateanxiety4 ///
    COGstateanxiety5 ///
    COGstateanxiety6 ///
)

replace COGstai6_total = . if COGstai6_missing > 0

label variable COGstai6_total ///
    "STAI-6 state anxiety total score (6-24)"


* 20-item equivalent score
gen COGstai6_equiv20 = COGstai6_total * (20/6)

label variable COGstai6_equiv20 ///
    "STAI-6 state anxiety score, 20-item equivalent (20-80)"


* Checks
summarize COGstai6_total COGstai6_equiv20
tab COGstai6_total, missing


* Drop temporary variable
drop COGstai6_missing

Download Stata .do file

stai_items <- paste0("COGstateanxiety", 1:6)

# Raw 6-item total score.
# rowSums(..., na.rm = TRUE) mirrors Stata egen rowtotal().
data$COGstai6_total <- rowSums(data[stai_items], na.rm = TRUE)

# Require all six items to be answered.
data$COGstai6_missing <- rowSums(is.na(data[stai_items]))
data$COGstai6_total[data$COGstai6_missing > 0] <- NA_real_

attr(data$COGstai6_total, "label") <-
  "STAI-6 state anxiety total score (6-24)"


# 20-item equivalent score.
data$COGstai6_equiv20 <- data$COGstai6_total * (20 / 6)

attr(data$COGstai6_equiv20, "label") <-
  "STAI-6 state anxiety score, 20-item equivalent (20-80)"


# Checks.
summary(data[c("COGstai6_total", "COGstai6_equiv20")])
table(data$COGstai6_total, useNA = "ifany")


# Drop temporary variable.
data$COGstai6_missing <- NULL

Download R file

* Raw 6-item total score.
* SUM() mirrors Stata egen rowtotal() by summing available nonmissing items.
COMPUTE COGstai6_total = SUM(
  COGstateanxiety1,
  COGstateanxiety2,
  COGstateanxiety3,
  COGstateanxiety4,
  COGstateanxiety5,
  COGstateanxiety6
).


* Require all six items to be answered.
COMPUTE COGstai6_missing = NMISS(
  COGstateanxiety1,
  COGstateanxiety2,
  COGstateanxiety3,
  COGstateanxiety4,
  COGstateanxiety5,
  COGstateanxiety6
).

IF (COGstai6_missing > 0) COGstai6_total = $SYSMIS.

VARIABLE LABELS COGstai6_total
  "STAI-6 state anxiety total score (6-24)".


* 20-item equivalent score.
COMPUTE COGstai6_equiv20 = COGstai6_total * (20 / 6).

VARIABLE LABELS COGstai6_equiv20
  "STAI-6 state anxiety score, 20-item equivalent (20-80)".


* Checks.
DESCRIPTIVES VARIABLES=COGstai6_total COGstai6_equiv20.
FREQUENCIES VARIABLES=COGstai6_total /MISSING=INCLUDE.


* Drop temporary variable.
DELETE VARIABLES COGstai6_missing.

EXECUTE.

Download SPSS .sps file