Question

I dont know what to do: Is there a significant difference between drug type and mean relative-change* of Cholesterol from screening to follow up?

* Relative Change = (Follow up - Initial) / Initial

Patient ID	Drug	Stomach Pain	Sex	Age	Height	Systolic BP	Diastolic BP	Exercise	Coffee Consumption	Alcohol Consumption	Weight	Weight3	Cholesterol	Cholesterol3	Triglycerides	Triglycerides3	HDL	HDL3	LDL	LDL3
1	B	Yes	F	22	67.13	124	78	180	1	> 2	138	145	197	182	152	135	43	34	151.6	145.8
2	B	Yes	M	22	63	122	70	0	2	< 2	115	122	181	151	59	57	60	48	120.1	102.1
3	B	No	F	22	72	124	80	90	0	< 2	190	190	190	169	117	86	41	37	147.1	130.6
4	A	Yes	M	22	69	120	70	120	5	> 2	115	105	131	133	54	72	58	67	72.1	64.8
5	B	Yes	M	25	73	138	92	40	2	> 2	160	165	172	166	93	139	49	40	121.5	123.8
6	B	Yes	M	22	67.5	100	72	0	0	< 2	150	165	233	229	176	144	42	38	188.2	188.7
7	A	Yes	M	23	73	128	78	0	2	< 2	154	150	194	148	79	80	49	26	143.7	120.7
8	A	No	M	24	71.5	128	74	90	0	< 2	185	187	155	148	89	73	45	50	108.6	96.8
9	A	Yes	F	23	73.5	124	82	60	1	> 2	178	166	234	175	307	88	28	28	201.1	145.6
10	A	Yes	M	22	72.25	130	88	40	0	0	158	163	201	203	88	112	50	40	149.6	161.2
11	A	No	M	26	73	130	86	0	1	< 2	188	195	258	276	299	199	30	21	223.2	251.8
12	A	No	M	22	64.25	120	74	0	0	> 2	150	150	212	228	52	61	69	60	142.2	167
13	B	Yes	M	22	64.25	120	74	0	4	0	123	131	137	165	158	147	29	39	105.5	123.6
14	B	No	F	27	65	100	68	180	2	> 2	138	133	285	229	98	89	69	61	214.4	166.6
15	A	No	M	22	59	124	84	180	0	> 2	143	140	218	172	101	96	46	21	170.4	149.5
16	B	Yes	F	24	67.5	122	68	210	1	< 2	139	151	167	152	71	91	51	37	114.9	113.5
17	A	Yes	F	22	71.5	118	70	60	0	< 2	156	155	170	158	81	91	42	40	126.7	116.5
18	A	Yes	M	22	69	125	76	180	0	< 2	150	154	157	140	86	88	37	34	118.6	104.6
19	A	Yes	M	24	68	122	74	100	5	> 2	135	128	215	176	71	53	62	46	151.9	129.2
20	A	No	M	25	74	134	88	180	0	< 2	219	220	194	207	71	130	40	33	152.9	171.9
21	A	No	F	28	71	110	80	60	2	> 2	173	173	207	231	107	145	53	47	152.3	181.7
22	A	Yes	M	22	68.5	116	84	280	0	0	151	165	198	199	80	126	44	46	152.7	151
23	A	Yes	M	23	75.5	124	73	60	1	0	182	183	189	262	47	230	50	31	138.2	227.3
24	A	Yes	M	24	70	124	72	360	0	< 2	161	163	216	203	95	121	35	28	179.5	173.1
25	B	Yes	F	22	72	126	88	120	0	0	176	173	212	173	140	88	43	35	166.8	136.6
26	B	Yes	F	26	72.5	138	82	0	0	< 2	177	175	175	169	77	78	46	52	127.8	115.8
27	B	Yes	F	23	72	120	68	60	1	< 2	174	197	158	172	57	126	34	30	123.1	140
28	B	No	F	20	74	118	76	0	2	0	234	217	115	146	95	110	26	33	87.5	111.2
29	B	No	F	28	66	138	82	120	0	0	150	160	228	224	480	373	29	28	191.3	190
30	A	Yes	F	23	74	124	76	60	0	< 2	149	150	164	164	94	92	43	44	119.5	118.5
31	B	Yes	M	22	70	118	72	0	0	< 2	156	160	149	149	155	65	37	29	109.5	119
32	A	Yes	F	23	71.5	124	70	180	3	< 2	168	170	211	183	63	60	52	44	158	138
33	B	Yes	F	22	73	122	76	0	0	< 2	182	170	191	185	99	101	39	39	150.4	144.4
34	B	No	F	40	75	128	80	0	5	> 2	217	230	277	243	240	218	71	28	202.2	211.5
35	B	No	M	22	65	128	82	120	1	< 2	190	201	178	191	52	77	41	56	136.2	133.8
36	A	Yes	F	25	69	124	78	150	5	< 2	159	154	157	112	93	71	41	38	114.5	72.9
37	A	No	M	22	73	126	73	180	0	0	191	199	151	155	44	94	42	44	108.3	109.5
38	A	No	M	24	59.5	122	72	100	0	0	140	140	209	165	71	71	41	42	166.9	121.9
39	B	No	F	23	71	116	72	120	0	0	183	186	209	147	95	124	37	29	170.5	116
40	B	Yes	F	26	71	132	78	90	0	0	162	167	197	216	47	64	43	43	153.2	172
41	B	No	M	29	69.5	130	82	0	3	< 2	181	169	226	208	126	86	38	36	186	170.6
42	B	No	F	30	70	112	72	0	5	< 2	196	199	127	139	116	69	32	31	93.1	106.9
43	A	No	M	25	65.5	120	72	180	2	> 2	141	143	180	162	85	93	41	46	137.6	114.5
44	B	No	F	25	74	117	77	0	2	0	230	217	117	146	95	110	25	33	87.5	111.2
45	A	Yes	M	24	70	122	76	100	5	> 2	135	128	215	177	71	53	62	46	151.9	129.2

Answer 1

I dont know what to do: Is there a significant difference between drug type and mean relative-change* of Cholesterol from screening to follow up?

* Relative Change = (Follow up - Initial) / Initial

Relative Change is calculated as follows.

Relative Change = (Cholesterol3 - Cholesterol) / Cholesterol

MINITAB is used to compare Relative Change between drug A and B.

MINITAB output

Two-Sample T-Test and CI: relative change, Drug

Method

μ₁: mean of relative change when Drug = A

µ₂: mean of relative change when Drug = B

Difference: μ₁ - µ₂

Equal variances are assumed for this analysis.

Descriptive Statistics: relative change

Drug	N	Mean	StDev	SE Mean
A	23	-0.057	0.152	0.032
B	22	-0.017	0.145	0.031

Estimation for Difference

Difference	Pooled StDev	95% CI for Difference
-0.0392	0.1486	(-0.1286, 0.0502)

Test

Null hypothesis	H₀: μ₁ - µ₂ = 0
Alternative hypothesis	H₁: μ₁ - µ₂ ≠ 0

T-Value	DF	P-Value
-0.88	43	0.382

Calculated t= -0.88, P=0.382 which is greater than 0.05, the level of significance.

Ho is not rejected. There is not sufficient evidence to conclude that there a significant difference between drug type and mean relative-change of Cholesterol from screening to follow up.

DATA:

Patient ID	Drug	Cholesterol	Cholesterol3	relative change
1	B	197	182	-0.07614
2	B	181	151	-0.16575
3	B	190	169	-0.11053
4	A	131	133	0.01527
5	B	172	166	-0.03488
6	B	233	229	-0.01717
7	A	194	148	-0.23711
8	A	155	148	-0.04516
9	A	234	175	-0.25214
10	A	201	203	0.00995
11	A	258	276	0.06977
12	A	212	228	0.07547
13	B	137	165	0.20438
14	B	285	229	-0.19649
15	A	218	172	-0.21101
16	B	167	152	-0.08982
17	A	170	158	-0.07059
18	A	157	140	-0.10828
19	A	215	176	-0.18140
20	A	194	207	0.06701
21	A	207	231	0.11594
22	A	198	199	0.00505
23	A	189	262	0.38624
24	A	216	203	-0.06019
25	B	212	173	-0.18396
26	B	175	169	-0.03429
27	B	158	172	0.08861
28	B	115	146	0.26957
29	B	228	224	-0.01754
30	A	164	164	0.00000
31	B	149	149	0.00000
32	A	211	183	-0.13270
33	B	191	185	-0.03141
34	B	277	243	-0.12274
35	B	178	191	0.07303
36	A	157	112	-0.28662
37	A	151	155	0.02649
38	A	209	165	-0.21053
39	B	209	147	-0.29665
40	B	197	216	0.09645
41	B	226	208	-0.07965
42	B	127	139	0.09449
43	A	180	162	-0.10000
44	B	117	146	0.24786
45	A	215	177	-0.17674