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Stats

Terms in this set (25)

Mean
Average of all numbers
Median
Middle number of data set, when lines up in ascending order
Mode
Most frequent number
How do you find the median with an even number of data elements
Find the middle two number and add them and divide the sum but 2
On a central tendency graph how do you determine mode
It is always the highest point in the graph
On a central tendency graph if the distribution is even, how is the mode determined
Mean/Median = Mode
What does a positively skewed distribution look like (graph)
"Tail" is going toward the higher number on the x-axis
What does a negatively skewed distribution look like (graph)
"Tail" is going toward the lower number on the x-axis
If the highest point on the graph is the mode, where are the median and mean located
Mean is always towards the tail, median is in the middle of the mean and mode
What happens to mean median and mode if the distribution is equal
They are all equal (mean=mode=median)
What modality (mean, median, mode) is least likely to be affected by outliers
Mode
What is standard deviation
Most important
Within + or - one what will the present in standard deviation be
68%
Within + or - two what will the present in standard deviation be
95%
Within + or - three what will the present in standard deviation be
99%
What do the variants represent
Average degree of which each point differs from the mean
What is a Z score
Related to dispersion
Describes a SINGLE data point
How far the datapoint is from the mean
+ 1 id going towards the higher numbers
-1 is going towards the lower number
Mean is the mid point
How is a Z score calculated
Data needed: mean, standard deviation, grade/point
Z score=(grade/point-mean)/standard deviation
How to determine how close a sample is to the true population mean
standard error mean and confidence intervals
What is the standard error of a mean
How far the dataset mean is from the true population mean
How is the standard error of a mean determined
standard deviation divided by the square root of n
N being samples
What 2 things can shrink the standard error of a mean
High sample number or low standard deviation
What are the confidence intervals
Range in which 95% of repeated measurements would be expected to fall
" If we repeated our experiment and collected 100 samples, 95% of the time we would get a mean that falls within the confidence interval range of the number."
How to calculate confidence intervals
You need: n, mean, standard deviation, standard error of a mean
You will probably be given n, mean and standard deviation
You will first calculate the standard error of a mean (standard deviation divided by the square root of n)
Finally the confidence interval is the mean +/- 1.96 * standard error of a mean
(The plus or minus means u do it twice, that will give u the two numbers for the range)
What is the difference between standard deviation and confidence interval
SD is for a dataset, descriptive characteristics of the samples within the data set
Whereas the CI does not describe the sample in the data set, its an inferred value of where the true mean lies for population
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