Background
Methods
Participants and procedures
The first group
The second group
Measurements
-
Low risk (score: 0–3): The participant is at low risk of health and other problems from his/her current pattern of use.
-
Moderate risk (score: 4–26): The participant is at risk of health and other problems from his/her current pattern of substance use.
-
High risk (score ≥ 27): The participant is at high risk of experiencing severe problems (health, social, financial, legal, relationship) as a result of his/her current pattern of use and is likely to be dependent.
Statistical analyses
Evaluation of model fit
Sample size considerations
Results
Cannabis use
Question
|
Format
|
χ
2
|
p
| |
---|---|---|---|---|
Outpatients PaP (n = 150)
|
Web (n = 1366)
| |||
2. In the past three months how often have you used cannabis? | 830.2 | <0.0005 | ||
- Never | 75.3 | 2.5 | ||
- One or two times | 3.3 | 3.9 | ||
- Monthly | 5.3 | 4.2 | ||
- Weekly | 6.0 | 15.4 | ||
- Daily or almost daily | 10.0 | 74.0 | ||
3. During the past three months how often have you had a strong desire or urge to use cannabis? | 381. 9 | <0.0005 | ||
- Never | 78.0 | 12.3 | ||
- One or two times | 4.0 | 14.0 | ||
- Monthly | 2.7 | 5.3 | ||
- Weekly | 6.7 | 18.4 | ||
- Daily or almost daily | 8.7 | 50.1 | ||
4. During the past three months how often has your use of cannabis led to health, social, legal or financial problems? | 110.9 | <0.0005 | ||
- Never | 88.6 | 45.0 | ||
- One or two times | 3.4 | 21.2 | ||
- Monthly | 2.0 | 13.3 | ||
- Weekly | 2.7 | 11.8 | ||
- Daily or almost daily | 3.4 | 8.7 | ||
5. During the past three months how often have you failed to do what was normally expected of you because of your use of cannabis? | 168.7 | <0.0005 | ||
- Never | 96.0 | 40.5 | ||
- One or two times | 0 | 22.3 | ||
- Monthly | 0.7 | 10.9 | ||
- Weekly | 2.7 | 15.6 | ||
- Daily or almost daily | 0.7 | 10.8 | ||
6. Has a friend or relative or anyone else ever expressed concern about your use of cannabis? | 147. 8 | <0.0005 | ||
- No, never | 60.2 | 35.3 | ||
- Yes, in the past three months | 9.3 | 17.2 | ||
- Yes, but not in the past three months | 6.0 | 47.5 | ||
7. Have you ever tried to control, cut down or stop using cannabis? | 157.7 | <0.0005 | ||
- No, never | 88.7 | 35.3 | ||
- Yes, in the past three months | 5.3 | 25.8 | ||
- Yes, but not in the past three months | 6.0 | 38.9 | ||
Cannabis involvement score (sum of responses to Q2-Q7) | 4.2 (8.7) | 22.8 (9.9) | −24.3* | <0.0005 |
Risk level according to ASSIST v3.0 | 874.3 | <0.0005 | ||
- Low (0–3) | 77.3 | 3.3 | ||
- Moderate (4–26) | 18.7 | 54.2 | ||
- High (≥27) | 4.0 | 42.5 |
Internal consistency
Testing for configural equivalence
Model description
|
RMSEA
|
CFI
|
χ
2
|
df
|
Δχ
2
|
Δdf
|
Statistical significance
|
---|---|---|---|---|---|---|---|
1. Configural model: no constraints imposed | 0.02 | 0.99 | 8.06 | 6 | - | - | - |
2. Factor loadings: constrained equally across groups | 0.03 | 0.97 | 45.44 | 19 | 37.38 | 13 | p < 0.0005 |
Testing for measurement equivalence
Question
|
Pen-and-paper (n = 150)
|
Web (n = 1366)
|
---|---|---|
Q2: In the past three months how often have you used cannabis? | 0.92 |
0.51
|
Q3: During the past three months how often have you had a strong desire or urge to use cannabis? | 0.98 |
0.62
|
Q4: During the past three months how often has your use of cannabis led to health, social, legal or financial problems? | 0.76 |
0.71
|
Q5: During the past three months how often have you failed to do what was normally expected of you because of your use of cannabis? | 0.24 |
0.67
|
Q6: Has a friend or relative or anyone else ever expressed concern about your use of cannabis? | 0.46 |
0.44
|
Q7: Have you ever tried to control, cut down or stop using cannabis? | 0.22 |
0.50
|
Testing for invariance across two random subsamples of the Web sample
Question
|
Web total sample (n = 1366)
|
Web subsample 1 n = 675
|
Web subsample 2 n = 691
|
p
1
|
---|---|---|---|---|
2. In the past three months how often have you used cannabis? | 1.0 | |||
- Never | 2.5 | 2.5 | 2.5 | |
- One or two times | 3.9 | 3.9 | 3.9 | |
- Monthly | 4.2 | 4.1 | 4.3 | |
- Weekly | 15.4 | 16.0 | 14.8 | |
- Daily or almost daily | 74.0 | 73.5 | 74.5 | |
3. During the past three months how often have you had a strong desire or urge to use cannabis? | 0.6 | |||
- Never | 12.3 | 12.6 | 12.2 | |
- One or two times | 14.0 | 15.3 | 12.6 | |
- Monthly | 5.3 | 5.3 | 4.9 | |
- Weekly | 18.4 | 17.9 | 18.8 | |
- Daily or almost daily | 50.1 | 48.9 | 51.5 | |
4. During the past three months how often has your use of cannabis led to health, social, legal or financial problems? | 0.8 | |||
- Never | 45.0 | 44.4 | 45.7 | |
- One or two times | 21.2 | 22.4 | 19.8 | |
- Monthly | 13.3 | 13.2 | 13.5 | |
- Weekly | 11.8 | 11.3 | 12.3 | |
- Daily or almost daily | 8.7 | 8.7 | 8.7 | |
5. During the past three months how often have you failed to do what was normally expected of you because of your use of cannabis? | 0.8 | |||
- Never | 40.5 | 41.5 | 39.4 | |
- One or two times | 22.3 | 21.0 | 23.7 | |
- Monthly | 10.9 | 10.8 | 11.1 | |
- Weekly | 15.6 | 15.7 | 15.2 | |
- Daily or almost daily | 10.8 | 11.0 | 10.6 | |
6. Has a friend or relative or anyone else ever expressed concern about your use of cannabis? | 0.3 | |||
- No, never | 35.3 | 34.2 | 36.0 | |
- Yes, in the past three months | 17.2 | 16.1 | 18.2 | |
- Yes, but not in the past three months | 47.5 | 49.6 | 45.7 | |
7. Have you ever tried to control, cut down or stop using cannabis? | 0.7 | |||
- No, never | 35.3 | 36.0 | 35.2 | |
- Yes, in the past three months | 25.8 | 24.7 | 26.8 | |
- Yes, but not in the past three months | 38.9 | 39.3 | 38.1 | |
Cannabis involvement score (sum of responses to Q2-Q7) | 22.8 (9.9) | 22.8 (9.8) | 22.8 (10.0) | 1.0 |
Risk level according to ASSIST v3.0 | 0.9 | |||
- Low (0–3) | 3.3 | 3.1 | 3.6 | |
- Moderate (4–26) | 54.2 | 53.8 | 53.8 | |
- High (≥27) | 42.5 | 43.1 | 42.5 |
Model description
|
RMSEA
|
CFI
|
χ
2
|
df
|
χ
2
/df
|
Δχ
2
|
Δdf
|
Statistical significance
|
---|---|---|---|---|---|---|---|---|
1. Configural invariance: no constraints imposed
|
0.03
|
0.99
|
26.80
|
14
|
1.9
|
-
|
-
|
-
|
2. Factor loadings: constrained equally across groups
|
0.02
|
0.99
|
32.31
|
19
|
1.7
|
5.51
|
5
|
p = 0.4
|
3. Factor loadings and variances: constrained equally
|
0.02
|
0.99
|
32.33
|
20
|
1.6
|
5.53
|
6
|
p = 0.5
|
4. Factor loadings, variances, and error covariances: constrained equally
|
0.02
|
0.99
|
38.76
|
28
|
1.4
|
11.97
|
14
|
p = 0.6
|