Data analysis workshop/ 1.25.10 am

Today we learned about statistical null hypothesis verses research hypothesis.

In a t-test, the Ho is always that the means in the two populations that we're comparing are equal.

The research hypothesis - depends on what we expect

We use the research hypothesis to determine whether our test is one-tailed or two-tailed. One-tailed predicts a direction, two-tailed means you aren't sure about the direction.

Central tendency: where most of the data are in a distribution - where the values cluster. Use mean when the distribution is equally distributed (normal distribution). Use median when you have a highly skewed distribution.

Measures of variation: how different do your samples need to be, for you to conclude that they're really different? Standard deviation - great for comparing two samples when you don't have replicates. 1 stdev describes 76% of the data; 2 stdev describe 98% of the date, standard error - use when you have multiple replicates (like we do in our data set!)

Control
mean median mode St. Dev. Variance St. Error
110.25 107.5 75 29.66812041 880.1973684 0.632526452

Emersion.5h
mean median mode St. Dev. Variance St. Error
1.666666667 0 0 2.5 6.25 0.372677996