The .UTL File
The .UTL file contains the estimated part-worths for each respondent. Each respondent's data are formatted across multiple lines. An example is as follows:
104 935 0 23 7
9.465 9.746 -9.999 -9.999 -9.999 -2.108 -1.305 -1.275 -0.547 -0.635
-9.999 -9.999 -9.999 -9.999 -1.665 -1.764 -4.172 -2.473 -4.131 -3.254
-2.473 -6.029 -4.550
Following is a description of each line:
Linee |
Field |
Description |
Notes |
1 |
1 |
Respondent Number |
Number identifies record |
|
2 |
Correlation |
A "-1" indicates Calibration Concepts were not shown and as a result a correlation was not calculated; consequently the Purchase Likelihood model cannot be used for simulations |
|
3 |
Merged Variables |
Always zero when generated by ACA |
|
4 |
Number of Utility Levels |
Number of levels in record |
|
5 |
Interview Duration |
Always a zero in ACA |
2 |
1 |
First Utility Level |
Value of level |
|
2 |
Second Utility Level |
Value of level |
... |
Remainder of Utility Levels |
And so on, for all existing utility levels. |
There can be up to 18 lines of part-worth utility levels; each line has 8 columns per level, up to 10 levels per line; up to a maximum of 180 levels. Each value has 3 places after the decimal point.
The STUDYNAME.ACD File (Audit Trail)
The STUDYNAME.ACD file contains an "audit trail" of the questionnaire for each respondent. The file contains information about which questions were presented and about the responses. In earlier versions of ACA, such as ACA v4 for DOS, this file also contained three sets of part-worths, computed at various stages of the interview. We expect that most ACA users will use the .ACD file generated by ACA with ACA/HB (Hierarchical Bayes estimation). ACA/HB does not use the three sets of part-worths available in previous versions of the .ACD file, so we have inserted "0.000" values to maintain compatibility with the prior .ACD file format.
There is one record for each respondent, in the order respondents appear in the STUDYNAME.UTL file.
Following is an example of one respondent's record in the audit trail file:
104 12 5 21
5 1 4 1 4 3 2 5 0 0 0 0
7 6 4 1 3 2 0 0 0 0 0 0
14 9 2 1 2 5 4 3 6 0 0 0
16 17 3 2 3 1 0 0 0 0 0 0
19 23 1 6 5 4 3 2 1 0 0 0
-1 -7 2 8 0 0 0 0 0 0 7
-6 -10 7 9 0 0 0 0 0 0 6
-9 -16 10 17 0 0 0 0 0 0 3
-17 -20 15 18 0 0 0 0 0 0 4
-1 -20 2 21 0 0 0 0 0 0 8
-6 -10 -19 8 9 18 0 0 0 0 4
-1 -16 -19 2 15 17 0 0 0 0 7
-1 -10 -16 2 9 15 0 0 0 0 7
-6 -10 -20 7 9 21 0 0 0 0 7
-8 -17 -21 6 16 17 0 0 0 0 7
-1 -7 -10 -15 2 8 9 17 0 0 7
-1 -9 -16 -19 2 10 15 21 0 0 7
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
4 5
1 6 9 15 21 0.000 12
2 7 10 16 17 0.000 99
1 7 10 16 17 0.000 24
2 6 9 14 20 0.000 55
0.000 0.000 0.000 0.000
First line:
The first line contains the respondent number (104); the number of pairs that were shown in the Pairs section of the interview (12), the number of attributes in the study (5); and the number of attribute levels in the study (21).
Attribute levels are assigned consecutive numbers. Numbers are assigned beginning with the levels of the first attribute, then the levels of the second attribute, and so on. For example, the chart below shows how numbers are assigned to the levels of the attributes in the questionnaire that generated this data file:
Body Type Configuration Color Manufacturer Price
Two-Door Sedan (1) Rear-Wheel Drive (6) Red (9) US Manufacturer (14) $16,000(17)
Four-Door Sedan (2) Front-Wheel Drive (7) Blue (10) Japanese Manufacturer (15) $18,000(18)
Hatchback (3) All-Wheel Drive (8) Green (11) European Manufacturer (16) $20,000(19)
Minivan (4) Yellow (12) $22,000(20)
Convertible (5) White (13) $24,000(21)
Second and next lines, the Importance Ratings:
Next follows one line for each attribute. Each line has 12 columns (unless there are more than 9 levels for any attribute, in which case the layout is expanded to 18 columns). These 12 columns allow for the maximum number of levels to be displayed (9), the two attribute levels that were shown, and the respondent's answer to the Importance question.
The numbers in the first and second columns in each line represent the attribute levels that were shown in the Importance Rating section. The number in the third column is the respondent's answer to the Importance question. Then, the remaining 9 columns have numbers for each level that show the preference rating for each level, in order, for as many levels as exist for the attribute. These numbers are ratings, where the "1" indicated the least-preferred level. Any remaining columns contain zeros.
Using our example record that has 5 attributes, the lines just described are lines 2-6:
5 1 4 1 4 3 2 5 0 0 0 0
7 6 4 1 3 2 0 0 0 0 0 0
14 9 2 1 2 5 4 3 6 0 0 0
16 17 3 2 3 1 0 0 0 0 0 0
19 23 1 6 5 4 3 2 1 0 0 0
The second line represents the second attribute (Drive Configuration); the first number, 7 (Front-Wheel Drive), and the next number, 6 (Rear-Wheel Drive) represent the attribute levels that were shown in the Importance Rating Section. The third number, 4, is the respondent's answer to the Importance question. The next numbers, 1, 3, and 2, indicate that the first level (Rear-Wheel Drive) was least preferred (1), the second level (Front-Wheel Drive) was most preferred (3), and the preference for the third level (All-Wheel Drive) was in between (2). The second attribute has only three levels, so the remaining columns on this line contain zeros.
Next lines, the Paired-Comparisons:
Next follows one line for each of the pairs that were shown in the Pairs section of the interview. Each line has 11 columns. These 11 columns allow for the maximum number of levels to be displayed in the Pairs (5 in each of 2 concepts) and one column for the respondent's answer. The numbers represent the levels that were shown. Numbers with negative signs indicate that the level appeared on the left side of the screen, and those without negative signs indicate that the level appeared on the right side of the screen. The final number on the line is the respondent's answer.
Using our example record that has 12 pairs, the lines just described are 7-18:
-1 -7 2 8 0 0 0 0 0 0 7
-6 -10 7 9 0 0 0 0 0 0 6
-9 -16 10 17 0 0 0 0 0 0 3
-17 -20 15 18 0 0 0 0 0 0 4
-1 -20 2 21 0 0 0 0 0 0 8
-6 -10 -19 8 9 18 0 0 0 0 4
-1 -16 -19 2 15 17 0 0 0 0 7
-1 -10 -16 2 9 15 0 0 0 0 7
-6 -10 -20 7 9 21 0 0 0 0 7
-8 -17 -21 6 16 17 0 0 0 0 7
-1 -7 -10 -15 2 8 9 17 0 0 7
-1 -9 -16 -19 2 10 15 21 0 0 7
The first of those lines represents the first pair; the first number, -1, indicates that level number 1, Two-Door Sedan, appeared on the left of the screen. The second number, -7, indicates that level number 7, Front-Wheel Drive, appeared on the left of the screen. Those levels were paired with the next two numbers, which appeared on the right of the screen: 2 (Four-Door Sedan) and 8 (All-Wheel Drive).
The final number in the line, 7, indicates the response to this Pairs question.
Next lines, the Utilities Before Calibrations:
In ACA v4, the next lines represent the part-worths for each level of each attribute, in order, for this respondent, prior to calibration. In ACA, we insert "0" values as placeholders. Each line has up to 10 part-worths.
Using our example record that has 23 attribute levels, the lines just described are 19-21:
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
The values are displayed for each level.
Next lines, the Prior Utilities:
In ACA v4 the next lines represent approximate part-worths for each level of each attribute, in order, for this respondent. These part-worths are based only on the information from the interview prior to the Pairs section. In ACA, we insert 0 values as placeholders. Each line has up to 10 part-worths.
Using our example record, the lines just described are 22-24:
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
The values are displayed for each level.
Next lines, the Contribution to the Utilities from the Pairs Section:
In ACA v4 the next lines represent part-worths for each level of each attribute, in order, for this respondent. These are the components of the part-worths from the Pairs section. In ACA, we insert 0 values as placeholders. Each line has up to 10 utilities.
Using our example record, the lines just described are 25-27:
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000
The values are displayed for each level.
Next line, Number of Calibration Concepts and Number of Attributes:
The next line contains two numbers that report the number of Calibration Concepts shown to the respondent and the number of attributes in each concept.
In our example record, this is line 28:
4 5
The first number, 4, indicates that 4 concepts were shown. The second number, 5, indicates that there were 5 attributes in each concept.
Next lines, Calibration Concepts:
Next, there is one line for each calibration concept. For as many columns as there were attributes in each concept, numbers indicate the attribute levels included in the concept. Then, the next column shows the calculated utilities for the concept (in ACA we set those to 0.000). The last column contains the respondent's purchase likelihood value for the concept.
In our example record, the lines just described are lines 29-32:
1 6 9 15 21 0.000 12
2 7 10 16 17 0.000 99
1 7 10 16 17 0.000 24
2 6 9 14 20 0.000 55
The previous line, 28, indicated there were 4 concepts, so there are 4 lines (29-32 ), one for each concept. Line 28 also indicated there were 5 attributes in each concept, so each of the 4 lines uses the first 5 columns to show which attribute levels were included in that concept. For example, the first five numbers in line 29 indicate these levels were shown: 1 (Two-Door Sedan), 6 (Rear-Wheel Drive), 9 (Red), 15 (Japanese Manufacturer), and 21 ($24,000). In ACA v4, the next number indicates the total utility for the concept. In ACA we put a value of 0.000 there as a placeholder. The last number, 12, represents the respondent's purchase likelihood value for the concept.
Last line, Calibrating Coefficients:
In ACA v4 the last line contains the calibrating coefficients and measure of fit from the logit regression, which is used to predict likelihoods of purchase and to weight the priors and pairs components when estimating "optimal" utilities. In ACA we insert "0.000" as placeholders for those values.
In our example record, the line just described is line 33:
0.000 0.000 0.000 0.000