BIOSTAT Flashcards
Sometimes called as measures of position. A measure can tell us whether a value is about the average, or whether it’s unusually high or low.
POINT MEASURES
are three values that split sorted data into four parts, each with an equal number of observations.
Quartiles
Is Q1 a lower quartile, median, or upper quartile?
lower quartile
Is Q2 a lower quartile, median, or upper quartile?
Median
Is Q3 a lower quartile, median, or upper quartile?
upper quartile
split the data into ten parts: The 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, 90th and 100th percentiles.
Decile
defined as the difference between the third and the first
quartile in the set of data. In symbol: IQR = Q3 - Q1
Interquartile Range
are unusual values that fall outside of an expected range of values.
Outliers
is a number where a certain percentage of scores fall below that number.
Percentiles
is an overview of your data. The statistics in the summary are the smallest value (minimum), the largest (maximum), the middle (median) and the first and third quartiles.
Five number summary
shows the spread and center of data. It is a graphical representation of the five number summary.
Box and Whiskers Plot
are a way to compare results from a test to a
“normal” population. The z-scores indicates how many standards a score is from the
mean.
Standard scores
-The simplest and easiest measure of variability.
- The difference between the lowest value and the highest value in set of data.
- For group data, range is the difference between upper limit of the highest-class interval and the lower limit of the lowest class interval.
- Most unreliable because its magnitude depends only on the extreme
Range
Three kinds of Range
Absolute Range, Total Tange, & Kelly Range
getting the difference between highest and lowest score.
Absolute Range
is the difference by subtracting lowest score from the highest score + 1.
Total Range
subtracting the 10th percentile from the 90th percentile.
Kelly Range
obtained by taking half the difference of the third and the first quartile.
Semi-interquartile range or Quartile Deviation
Defined as the average deviation of all observation from the mean. We can compute how far observations deviate from the mean by subtracting the mean from the values of each observation.
Mean Deviation
Is the mean of the squared deviation of the observations for their arithmetic mean.
Variance (s^2)
The most widely used measure of variations. It is the square root of the variance.
Standard Deviation
the ratio of standard deviation and the mean, which is express in percent.
Coefficient of Variations
