Here\'s the question that\'s got me up all night: A medical researcher wishes to
ID: 2919046 • Letter: H
Question
Here's the question that's got me up all night:A medical researcher wishes to test the effects of two diets andthe time of day on the sodium level in a person's blood. Eightpeople are randomly selected and two are randomly assigned to eachof the four groups.
Diet Type
Time I II
8am 135 138
145 141
8pm 155 171
162 191
a) Does diet type and time of day effect average sodium level in aperson's blood?
b) PLot the sample means of diet type versus sodium level for eachtime of day. Can you detect an interaction? Discuss.
Man, I am lost with this.
Thanks in advance
Explanation / Answer
It's very simple! Diet Type Time I II 8am 135 138 145 141 8pm 155 171 162 191 (a) calculate the mean of 8am (for type I and II) = (135+138+145+141) /4 = 559/4= 139.75 calculate the mean of 8pm (for type I and II) = (155+171+162+191) /4 = 679/4= 169.75 So, is there a "main effect" for time? YES: Those in the 8am grouphave, on average, lower sodium levels than those in the 8pmgroup. calculate the mean of type I (for 8am and 8pm) = (135+145+155+162)/ 4 = 597/4= 149.25 calculate the mean of type II (for 8am and 8pm) = (138+141+171+191)/ 4 = 641/4= 160.25 So, is there a "main effect" for type? YES: Those in the type Igroup have, on average, lower sodium levels than those in the typeII group. (b) as far as the interaction...there are 4 treatments, or groups:(1) 8am,typeI; (2) 8am,typeII; (3) 8 pm,typeI; (4) 8pm,typeII. Calculate the mean for each group: (1) 8am,typeI = 140 (2) 8am,typeII = 139.5 (3) 8 pm,typeI = 158.5 (4) 8pm,typeII = 181 Now, the x axis is type, and the y axis is sodium level. Use onesymbol for 8 am and another for 8 pm. Connect the respectivedots! If you need to see a sample, download this document and simplechange the numbers: http://core.ecu.edu/psyc/wuenschk/docs30/Factorial-Basics.doc Best of luck!