Data analysis/Jan. 27

Standard deviation shows relationship between two things. Standard error is for one thing. Using one, find the average of the replicates. Then take the standard deviation divided by the square root of the total of the average count. If the error is say, "6", it would be +6 or -6. One STDEV is 68.2% of the data under a curve. We talked about when to use standard deviation and when to use STDEV error when you don't have replicants.

What is the level of significance (alpha)? It's where we choose our level of cut-off for distinguishing between a true signal and chance. This is an arbitrary choice. How willing are we to make a mistake? For what we are doing, a one in twenty chance is okay (90% of the time). This would show up at +5 and -5 on a bell curve. Choose alpha before conducting the experiment.

The P-value in output from your statistical test. It's a probability that your statistical null hypothesis is correct. If P-value = 0.06, "There is a 6% probability due to chance," then there's a six percent chance that the mean of the control = the mean of the experimental treatment. At 5% we accepted the null hypothesis. With alpha of 6%, "P" is greater than alpha.

If P-value = 0.0001 (one in 10K), then there's a one in ten thousand chance that random fluctuations alone can account for the differences in mean that we observe. Here is a very small chance that the experiment result is random. With alpha of 5%, "P" is much less than alpha. "P" <>

The statistical null hypothesis asks how does the control equal the experiment? You can never accept a null hypothesis. It's the "t" value that we actually interpret. Say "fail to reject." :0

The value of the "T" statistic doesn't depend on your means, that's why we go to "P" value, which is something that we can compare to any statistical test, as long as you know what you null hypothesis is.

What's a research hypothesis: emerson slows growth because snails need to be in the water to grow their shells. Our control is going to grow more than our emersion, so this is a one-tailed test. The statistical null hypothesis is that the control and the "emersion" are the same, so fail to reject.

Excel shows you that a Exponent is next is with an "E" (26.4E-13)
For error bars in Excel you have to set a custom value. Highlight the graph, click layout, then click error bar.
Directionality in a one-tailed test, one tail is covered.