Flashcards in CH 3 Deck (23):
Find u = sum of population.
N = number of values in data set
Population mean = u/N
Middle value WHEN numbers are arranged in ascending order.
Describes the average or typical data value.
Three measures = mean, median, mode
When data set is skewed
Median is preferred measure
When data set is not skewed
Mean is best
s^2 = sum x^2 - (sum x)^2/n) / n-1
n = sample size
Degree to which the data are spread out.
Population standard deviation
o^2 = sum (x - u)^2 / N
u = population mean
N = observations in the population
Sample standard deviation
Take square root of sample variance.
Histogram must be bell-shaped
- 68% of data lie within 1 standard deviation of the mean
- 95% lie within 2
- 99.7% lie within 3
Empirical rule calculation
x + s
Higher standard deviation is ___.
k = standard deviation
z = (x-u)/o
x = weight of baby born in week x
u = mean value
o = standard deviation
Median of the data
Median of the lower half of the data set.
Median of the higher half of the data set
Interquartile range = Q3 - Q1
Are cutoffs for determining outliers:
Q1 - 1.5(IQR)
Q3 + 1.5(IQR)
A data point is considered an outlier IF
It is less than the lower fence or greater than the upper fence
5 number summary
= smallest and largest numbers in the data set, Q1, Median, and Q3