00:01
So for this question, we're looking at an experiment run by scientists, checking to see how b12 was controlled and its effects on different chemicals in the body.
00:12
So i actually pulled this table from the published experiment because i thought this would be easier to understand than the table provided.
00:22
So here, you can kind of just ignore the tumor necrosis factor alpha because we're more concerned in this question about leptin, mcp1, and il6.
00:34
So here you can see you have both the four weeks reading when they're being fed on either their limited diet or their diet without any b12 and their results at 12 weeks.
00:48
So their limited diet means they have some b12 but not very much.
00:54
It's decreased.
00:54
Whereas the non -diet means they have little b -12, but they're fed pectin in their diet, which inhibits the absorption of b -12.
01:07
So any b -12 found in their diet is not going to be absorbed for the most part.
01:13
So here they're basically saying they have no b -12 in their diet.
01:17
So if you look among each of these, you can see that the limited diet typically has a small increase in each.
01:25
Of these adipocytokines, whereas the none or no b12 in the diet causes a larger increase for the most part in each of these chemicals.
01:42
So for part a, they're asking about the significant difference between the control group and the limited or no b12 diet and their difference between each of them.
01:55
So the way to go about this is to look at the mean value, which is going to be that provided value, and to add or subtract the standard deviation from each of these, and you'll get a range of numbers.
02:13
So for the control group here, you would get about 113 .5 to 220 .5.
02:23
And you have to do this for each of these groups.
02:27
So for the limited, you would get 125 .9 to a range of 136 .1.
02:39
So here you just have to expand the mean with the standard deviation range to get a range of values.
02:49
And this is because this standard deviation is telling us where the true mean value, of the real concentration of these molecules lies in each of these groups.
03:04
So because we have a small sample group, the standard deviation between each of these animals or the mean value they get for each of these animals actually ranges by a pretty significant amount.
03:18
So if you do that for each of these values to get a range, you should get a table that looks like this.
03:26
So here you'd be able to see the least amount of range for the mean value and the highest amount of range.
03:36
If you're looking for a significant difference, you're looking for a value that has no overlap.
03:42
So here you can see that the highest value for your tumor necrosis factor for the control group would be about 120 .5 picograms per milliliter.
03:53
Whereas the smallest possible mean value for the limited diet of tumor necrosis factor would be 125 .9 pico grams per milliliter.
04:04
So you know there's no overlap between the true mean value between these two groups.
04:10
So you can say for certain that your limited group should always have a larger tumor necrosis value factor than your control group.
04:19
This is opposed to say the left -in value where you do have this overlap, where the max value for the control group is higher than the minimum value for the limited group.
04:32
So here you wouldn't be able to say for certain that there was a statistical difference between the two.
04:38
It's possible that the rats in the limited group will have a mean value of 5 .6 pheograms per millilitre, or milligrams per miller, i believe.
04:49
Whereas your control group could have a 5 .7 normally.
04:55
So there you'd be able to see that there is practically no difference between the two and that one value is not higher than the other.
05:04
So if you look for all these missed overlaps in the week four column, you'll see that i've marked them with this blue cross...