Instructions: Answer the questions below using Microsoft Excel, SAS or another statistical analysis program.The data for questions 1 & 2 are located in an Excel spreadsheet on Canvas in the Exercises section. You will be using the same dataset for questions 1 and 2. Data for question three is provided below. Make sure you read through each question completely.

1. For the following questions, you will be using several methods to investigate the precision/ reliability of 50 individuals who completed replicate 24-hour recalls. Specifically, you will be investigating the reproducibility of total fat intake (g) and Vitamin A intake (RAE)[1] (mcg).

a. Plot the fat intake from the first 24-hour recall on the x-axis and the second 24-hour recall on the y-axis (paste plot below).How well do the estimates of intake seem to correlate (comment without calculating a correlation coefficient)?

b. Plot the Vitamin A intake from the first 24-hour recall on the x-axis and the second 24-hour recall on the y-axis (paste plot below).How well do the estimates of intake seem to correlate (comment without calculating a correlation coefficient)?

c. Use Excel to calculate the Pearson correlation coefficient for dietary fat intake and Vitamin A intake. Based on this information, which has better reliability and why do you think that is the case?

	Pearson r
Total Fat Intake (g)
Vitamin A Intake (RAE) (mcg)

	24 Hour Recall- Day 1	24 Hour Recall- Day 2	FFQ
ID	Total Fat (g)	Vitamin A (RAE) (mcg)	Total Fat (g)	Vitamin A (RAE) (mcg)	Total Fat (g)
21005	101.42	127	93.24	200	149.12
21006	43	245	39.7	248	13.7
21007	32.86	199	33.86	161	18.96
21008	107.95	455	74.51	816	229.14
21009	235.64	835	200.6	532	342.2
21010	60.87	423	51.13	394	70.1
21012	113.14	336	112.68	89	191.3
21013	103.38	38	21.79	22	209.6
21014	70.65	406	58.73	989	73.68
21015	45.75	650	89.17	913	11.5
21016	70.73	586	57.21	628	78.66
21017	70.08	99.5	74.32	151	86.34
21018	24.92	143	72.82	982	56
21019	23.33	56	22.01	131	1.43
21020	132.01	965	118.65	145	276.33
21022	47.23	349	33.9	440	6.77
21023	141.27	617	112.32	880	223.75
21024	43.87	553	49.76	2630	50.76
21025	38.28	61	74.78	938	9.48
21026	98.43	292	13.32	91	218.4
21027	114.42	859	96.79	446	189.47
21028	48.28	804	46.63	776	63.26
21029	115.8	777	186.13	1391	278.54
21031	42.25	459	36.8	576	56.23
21032	66.45	161	31.41	230	12.4
21033	53.74	203	49.09	588	34.69
21035	51.78	1328	25.3	851	39.12
21036	66.32	283	60.93	246	41.6
21037	75.87	706	82.63	636	48.65
21038	93.02	201	15.95	170	188.42
21039	46.02	1108	52.39	1382	97.43
21040	40.63	566	54.35	510	3.82
21041	70.4	544	41.64	214	36.6
21043	42.08	138	52.61	342	106.6
21045	49.17	1086	94.11	753	8.99
21046	49.54	441	93.19	857	11.6
21047	102.51	107	93.21	1423	171.4
21048	73.06	346	109.36	45	69.34
21049	82.87	437	77.59	421	52.23
21050	57.43	48	81.35	270	32.42
21051	134.11	808	104.68	308	263.4
21052	88.56	407	138.8	531	38.2
21054	18.37	47	42.5	947	3.68
21055	85.87	283	44.98	218	114.68
21057	115.96	460	187.68	811	197.56
21058	63.64	214	45.38	265	41.73
21059	22.97	203	88.58	874	99.4
21060	35.86	661	119.6	232	5.77
21061	64.06	658	74.84	177	40.84
21062	62.96	351	61.97	1370	45.5

[1] RAE = Retinol Activity Equivalents