Lecture 2- Standard error Flashcards
How to calculate variance
How much each score differs from the mean, squared, sum, divided by n(-1)
What is the standard deviation
square root of variance - in a comparative unit of measurement.
Definition of standard error
The amount of standardised deviation between the population and the sample- how much the sample mean deviates from the estimated population mean.
How to calculate standard error
sample SD/ square root of N
explain the 95% confidence intervals
IN a normal distribution 95% of the data falls 2SD away from the mean. They show how much error we have in our sample and where the population mean might fall.
How to calculate the 95% confidence intervals
mean =/- (1.96 x SE)
Explain the difference between error bars showing : SD, SE, 95% CI
SD= the amount of standardised deviation in your sample,
SE= the amount of deviation between the sample mean and the population mean
95% CI= where the population mean might fall.
WHy does a t value bellow 1 mean there is no effect
t values are calculated by dividing the effect by the error.
The effect- is the difference between the two means.
The error- is the amount of standard error in the sample.
Therefore, if your error is larger than your effect then the t value will be bellow 1.
How can you reduce error
Have a large sample.
