Oct 16 Bio Reading Statistics
- Categorical vs categorical: chi squared
- Categorical vs continuous: t-test
- Continuous vs continuous: linear regression
Standard Error Bars
Standard error of the mean indicates uncertainty in a calculated mean. It measures precision.
Confidence interval is the range a value is expected to fall within.
SEM = SD/sqrt(sample size)
Used to compare observed with expected (theoretical) data to determine whether certain things are due to chance or are significant.
Used to determine if there is a significant difference between means.
Analysis of Variance (ANOVA)
Used to compare means of 2+ sets of data and determine which variables affect which.
Regression and Correlation
Done to determine the slope of the relationship (if it exists) between two variables.
p-values and significance
- Specify null hypothesis
- Calculate test statistic
- Determine probability of getting by chance a test statistic at least as large as the one calculated.
P-value indicates probability of rejecting null hypothesis. A P value of 0.01 means a 1% chance that the null hypothesis has wrongly been rejected. 0.05 is generally considered to be enough.
The problem of two random events (before they happen) is the probability of each multiplied together.
When there are multiple ways for an event to occur, add the probabilities as long as they're independent.