* These examples are derived from the handouts on 2 sample tests.

* First, we will (erroneously) treat these as 2 independent
* samples.  SPSS will give us the results for 2 sample
* tests, cases II and III.  'Equal Variances assumed'
* corresponds to case II (sigma 1 = sigma 2 = sigma), 
* 'Equal variances not assumed' corresponds to case III
* (sigma 1 does not equal sigma 2).  Note that SPSS uses a
* different formula for Case III d.f. than I have been using.
* I do not know where their formula comes from or if it can be
* considered correct.
DATA LIST FREE / Sex Score.
BEGIN DATA.
1 26
2 30
1 28
2 29
1 28
2 28
1 29
2 27
1 30
2 26
1 31
2 25
1 34
2 24
1 37
2 23
END DATA.
VARIABLE LABELS SEX 'Sex of Respondent' SCORE 'Respondents score'.
VALUE LABELS SEX 1 'Male' 2 'Female'.
T-TEST /GROUPS SEX (1,2) /VARIABLES SCORE.

* Now we will treat this as a matched pairs problem.  SPSS will
* give us the results for 2 sample tests, case 4.
DATA LIST FREE / HScore Wscore.
BEGIN DATA.
26 30
28 29
28 28
29 27
30 26
31 25
34 24
37 23
END DATA.
VARIABLE LABELS HScore 'Husbands score' WScore 'Wifes score'.
T-TEST /PAIRS HScore WScore.

* Finally, using different data, we'll show what happens when Model II is used
* with a large data set when Model V is technically called for.  Note that results
* are virtually identical to what we got when we hand-calculated the results
* for case V.  Later, we'll show another and more exact way to get SPSS to
* handle case V.

DATA LIST FREE / Group Recover Freq.
BEGIN DATA.
1 1 75
1 0 25
2 1 65
2 0 35
END DATA.
Value labels Group 1 "Group A" 2 "Group B"/ 
    Recover 1 "Recovered" 0 "Didn't Recover"/.
Weight by Freq,

T-TEST
  GROUPS=group(1 2)
  /MISSING=ANALYSIS
  /VARIABLES=recover
  /CRITERIA=CIN(.95) .