Table 27.1 Item subtotal summaries on one line

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(controlled by ISUBTOT=, UDECIMALS=, REALSE=)

These summarize the measures from the main analysis for all items selected by ISUBTOT= (Table 27), including extreme scores.

 

Table

27.2 Measure sub-totals bar charts, controlled by ISUBTOT=

27.3 Measure sub-totals summary statistics, controlled by ISUBTOT=

 

Subtotal specification is: ISUBTOTAL=$S1W1

 

EXTREME AND NON-EXTREME SCORES

(NON-EXTREME SCORES ONLY)

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| ITEM    MEAN     S.E.  OBSERVED  MEDIAN   REAL       REAL     ITEM |

| COUNT  MEASURE   MEAN    S.D.          SEPARATION RELIABILITY CODE |

|--------------------------------------------------------------------|

|     18    -.76    1.03    4.26   -1.96    3.73        .93     *    |

|     10   -4.25     .57    1.70   -3.83    1.07        .53     0    |

|      2    4.80     .00     .00    4.80     .00        .00     1    |

|      2    5.47     .66     .66    5.47     .00        .00     2    |

|      1    2.24       -     .00    2.24     .00        .00     3    |

|      3    2.04     .75    1.05    1.95    1.29        .62     4    |

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UMEAN=0 USCALE=1

 

Subtotal specification is: ISUBTOTAL=$S1W1

identifies the columns in the item label to be used for classifying the item by $S1W1 or whatever, using the column selection rules.

EXTREME AND NON-EXTREME SCORES

All items with estimated measures

NON-EXTREME SCORES ONLY

Items with non-extreme scores (omits items with 0% and 100% success rates)

ITEM COUNT

count of items. "ITEM" is the name assigned with ITEM=

MEAN MEASURE

average measure of items

S.E. MEAN

standard error of the average measure of items

OBSERVED S.D.

population standard deviation of the items. Sample standard deviation is OBSERVED S.D. * sqrt ( COUNT / (COUNT-1))

MEDIAN

the measure of the middle item

REAL/MODEL SEPARATION

the separation coefficient: the "true" adjusted sample standard deviation / root-mean-square measurement error of the items (REAL = inflated for misfit).

REAL/MODEL RELIABILITY

the item measure reproducibility = ("True" item measure variance / Observed variance) = Separation² / (1 + Separation²)

ITEM CODE

the classification code in the item label. The first line, "*", is the total for all items. The remaining codes are those in the item columns specified by $S1W1 or whatever, using the column selection rules.

SUBTOTAL RELIABILITY

the reliability (reproducibility) of the means of the subtotals = true variance / observed variance = (observed variance - error variance) / observed variance.

Observed variance = variance of MEAN MEASURES

Error variance = mean-square of the S.E. MEAN

 

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| ITEM      MEAN DIFFERENCE        Welch       |

| CODE CODE MEASURE   S.E.    t    d.f.  Prob. |

|----------------------------------------------|

| 0    1      -9.06    .57 -15.95   10    .000 |

| 0    2      -9.72    .87 -11.14   10    .000 |

| 0    4      -6.29    .94  -6.71   11    .000 |

| 1    2       -.66    .66  -1.00    2    .423 |

| 1    4       2.77    .75   3.71    3    .034 |

| 2    4       3.43   1.00   3.44    3    .041 |

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ITEM CODE

the classification code in the item label for subtotal "1"

CODE

the classification code in the item label for subtotal "2"

MEAN DIFFERENCE

difference between the mean measures of the two CODE subtotals, "1" and "2"

MEASURE

size of the difference between "1" and "2"

S.E.

standard error of the difference = sqrt ( (S.E. Mean "1")² + (S.E. Mean "2")² )

t

Student's t = MEASURE / S.E.

d.f.

Welch's degrees of freedom

Prob.

probability of Student's t. See t-statistics.