Statistics Flashcards
What is the Arithmetic Mean?
The sim of all the inputs divided by the number of them. Usually called the Average.
What is the Mode?
The data item that occurs most frequently. Just look for the most frequently occurring number
What is the Median?
The middle number in a sequence, if there is an even number take the Mean of the middle two!
What is the Deviation?
It is the difference between the actual data and the arithmetic mean of the data set.
How do you get variance from deviation?
You square each deviation to get rid of the negative numbers and then take the arithmetic mean of them.
What is variance?
It is the mean of the squared deviations.
What is standard deviation?
Square root of the variance. Gets you back into numbers that are similar to the original data.
What is Correlation?
The strength of the relationship between two sets of variables.
What is regression?
Determines the Nature of the relationship between two variables.
What is a Normal Distribution?
If you take enough samples of data then the will form a bell curve shape around the mean. This is how we get to SD and SEM.
How do you estimate population level Standard Deviation, o?
You take SDsample x Square root(n/n-1)
What is Standard Error?
ITs the Standard deviation of the Means. If you did lots of different sample groups of the population and plotted there means they would be normally distributed on a bell curve. The mean of this curve will be the population mean, u. This curve has a SD called SEM.
What is the calculation for SEM?
SE= SDpopulation/Square root n
What is a 95% confidence level?
It is 2 SEMs away from the population mean. or 1.96 to be precise. Similar to 2 SDs.
How do we get a 95% Confidence Interval?
Sample Mean +/- 1.96x population SD o/square root n