Data examination

Here we are looking at several variables, instead of each of IV and DV. This is called multiple regression. We will discuss it later.

Download example file:

elemapi.sav

elemapi.sps

 display labels.

Data Label description
		Variable Labels
Variable	Position	Label
snum	1	school number
dnum	2	district number
api00	3	api 2000
api99	4	api 1999
growth	5	growth 1999 to 2000
meals	6	pct free meals
ell	7	english language learners
yr_rnd	8	year round school
mobility	9	pct 1st year in school
acs_k3	10	avg class size k-3
acs_46	11	avg class size 4-6
not_hsg	12	parent not hsg
hsg	13	parent hsg
some_col	14	parent some college
col_grad	15	parent college grad
grad_sch	16	parent grad school
avg_ed	17	avg parent ed
full	18	pct full credential
emer	19	pct emer credential
enroll	20	number of students
mealcat	21	Percentage free meals in 3 categories

우리가 관심이 있는 데이터는
2000년의 수학능력 (api00)
% 무료급식
% 풀타임 교원
k-3까지의 평균 클래스사이즈

이에 대한 부분적 자료 먼저 살펴보기 위해서는

list 
  /variables api00 acs_k3 meals full
  /cases from 1 to 10.

 api00 acs_k3 meals     full

   693    16     67    76.00
   570    15     92    79.00
   546    17     97    68.00
   571    20     90    87.00
   478    18     89    87.00
   858    20      .   100.00
   918    19      .   100.00
   831    20      .    96.00
   860    20      .   100.00
   737    21     29    96.00


Number of cases read:  10    Number of cases listed:  10

descriptive /var = all .

Descriptive Statistics
	N	Minimum	Maximum	Mean	Std. Deviation
school number	400	58	6072	2866.81	1543.811
district number	400	41	796	457.74	184.823
api 2000	400	369	940	647.62	142.249
api 1999	400	333	917	610.21	147.136
growth 1999 to 2000	400	-69	134	37.41	25.247
pct free meals	315	6	100	71.99	24.386
english language learners	400	0	91	31.45	24.839
year round school	400	0	1	.23	.421
pct 1st year in school	399	2	47	18.25	7.485
avg class size k-3	398	-21	25	18.55	5.005
avg class size 4-6	397	20	50	29.69	3.841
parent not hsg	400	0	100	21.25	20.676
parent hsg	400	0	100	26.02	16.333
parent some college	400	0	67	19.71	11.337
parent college grad	400	0	100	19.70	16.471
parent grad school	400	0	67	8.64	12.131
avg parent ed	381	1.00	4.62	2.6685	.76379
pct full credential	400	.42	100.00	66.0568	40.29793
pct emer credential	400	0	59	12.66	11.746
number of students	400	130	1570	483.47	226.448
Percentage free meals in 3 categories	400	1	3	2.02	.819

examine
  /variables=acs_k3
  /plot histogram stem boxplot .

Descriptives
			Statistic	Std. Error
avg class size k-3	Mean		18.55	.251
	95% Confidence Interval for Mean	Lower Bound	18.05
		Upper Bound	19.04
	5% Trimmed Mean		19.13
	Median		19.00
	Variance		25.049
	Std. Deviation		5.005
	Minimum		-21
	Maximum		25
	Range		46
	Interquartile Range		2
	Skewness		-7.106	.122
	Kurtosis		53.014	.244

Histogram

avg class size k-3 Stem-and-Leaf Plot

 Frequency    Stem &  Leaf

     8.00 Extremes    (=<14.0)
     1.00       15 .  &
      .00       15 .
    14.00       16 .  0000000
      .00       16 .
    20.00       17 .  0000000000
      .00       17 .
    64.00       18 .  00000000000000000000000000000000
      .00       18 .
   143.00       19 .  00000000000000000000000000000000000000000000000000000000000000000000000
      .00       19 .
    97.00       20 .  000000000000000000000000000000000000000000000000
      .00       20 .
    40.00       21 .  00000000000000000000
      .00       21 .
     7.00       22 .  000
      .00       22 .
     3.00       23 .  0
     1.00 Extremes    (>=25.0)

 Stem width:     1
 Each leaf:       2 case(s)

 & denotes fractional leaves.

Boxplot

frequencies
  /var acs_k3.

avg class size k-3
		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	-21	3	.8	.8	.8
	-20	2	.5	.5	1.3
	-19	1	.3	.3	1.5
	14	2	.5	.5	2.0
	15	1	.3	.3	2.3
	16	14	3.5	3.5	5.8
	17	20	5.0	5.0	10.8
	18	64	16.0	16.1	26.9
	19	143	35.8	35.9	62.8
	20	97	24.3	24.4	87.2
	21	40	10.0	10.1	97.2
	22	7	1.8	1.8	99.0
	23	3	.8	.8	99.7
	25	1	.3	.3	100.0
	Total	398	99.5	100.0
Missing	System	2	.5
Total		400	100.0

compute filtvar = (acs_k3 < 0).
filter by filtvar.
list cases
  /var snum dnum acs_k3.

     snum    dnum acs_k3

      600     140   -20
      596     140   -19
      611     140   -20
      595     140   -21
      592     140   -21
      602     140   -21


Number of cases read:  6    Number of cases listed:  6

filter off.
IF (acs_k3<0) racs_k3=ABS(acs_k3).
IF (acs_k3>=0) racs_k3=acs_k3.
EXECUTE.

frequencies
  variables=full
  /format=notable
  /histogram .

Histogram for variable full

pct full credential
		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	0.42	1	.3	.3	.3
	0.45	1	.3	.3	.5
	0.46	1	.3	.3	.8
	0.47	1	.3	.3	1.0
	0.48	1	.3	.3	1.3
	0.5	3	.8	.8	2.0
	0.51	1	.3	.3	2.3
	0.52	1	.3	.3	2.5
	0.53	1	.3	.3	2.8
	0.54	1	.3	.3	3.0
	0.56	2	.5	.5	3.5
	0.57	2	.5	.5	4.0
	0.58	1	.3	.3	4.3
	0.59	3	.8	.8	5.0
	0.6	1	.3	.3	5.3
	0.61	4	1.0	1.0	6.3
	0.62	2	.5	.5	6.8
	0.63	1	.3	.3	7.0
	0.64	3	.8	.8	7.8
	0.65	3	.8	.8	8.5
	0.66	2	.5	.5	9.0
	0.67	6	1.5	1.5	10.5
	0.68	2	.5	.5	11.0
	0.69	3	.8	.8	11.8
	0.7	1	.3	.3	12.0
	0.71	1	.3	.3	12.3
	0.72	2	.5	.5	12.8
	0.73	6	1.5	1.5	14.3
	0.75	4	1.0	1.0	15.3
	0.76	2	.5	.5	15.8
	0.77	2	.5	.5	16.3
	0.79	3	.8	.8	17.0
	0.8	5	1.3	1.3	18.3
	0.81	8	2.0	2.0	20.3
	0.82	2	.5	.5	20.8
	0.83	2	.5	.5	21.3
	0.84	2	.5	.5	21.8
	0.85	3	.8	.8	22.5
	0.86	2	.5	.5	23.0
	0.9	3	.8	.8	23.8
	0.92	1	.3	.3	24.0
	0.93	1	.3	.3	24.3
	0.94	2	.5	.5	24.8
	0.95	2	.5	.5	25.3
	0.96	1	.3	.3	25.5
	1	2	.5	.5	26.0
	37	1	.3	.3	26.3
	41	1	.3	.3	26.5
	44	2	.5	.5	27.0
	45	2	.5	.5	27.5
	46	1	.3	.3	27.8
	48	1	.3	.3	28.0
	53	1	.3	.3	28.3
	57	1	.3	.3	28.5
	58	3	.8	.8	29.3
	59	1	.3	.3	29.5
	61	1	.3	.3	29.8
	63	2	.5	.5	30.3
	64	1	.3	.3	30.5
	65	1	.3	.3	30.8
	68	2	.5	.5	31.3
	69	3	.8	.8	32.0
	70	1	.3	.3	32.3
	71	3	.8	.8	33.0
	72	1	.3	.3	33.3
	73	2	.5	.5	33.8
	74	1	.3	.3	34.0
	75	4	1.0	1.0	35.0
	76	4	1.0	1.0	36.0
	77	2	.5	.5	36.5
	78	4	1.0	1.0	37.5
	79	3	.8	.8	38.3
	80	10	2.5	2.5	40.8
	81	4	1.0	1.0	41.8
	82	3	.8	.8	42.5
	83	9	2.3	2.3	44.8
	84	4	1.0	1.0	45.8
	85	8	2.0	2.0	47.8
	86	5	1.3	1.3	49.0
	87	12	3.0	3.0	52.0
	88	6	1.5	1.5	53.5
	89	5	1.3	1.3	54.8
	90	9	2.3	2.3	57.0
	91	8	2.0	2.0	59.0
	92	7	1.8	1.8	60.8
	93	12	3.0	3.0	63.8
	94	10	2.5	2.5	66.3
	95	17	4.3	4.3	70.5
	96	17	4.3	4.3	74.8
	97	11	2.8	2.8	77.5
	98	9	2.3	2.3	79.8
	100	81	20.3	20.3	100.0
	Total	400	100.0	100.0

frequencies
  variables=full  .

IF (full  <= 1) rfull=full  * 100.
IF (full > 1) rfull=full.
EXECUTE.