Exam #1 Flashcards
Summation of x divided by n
mean
Summation of (x- pop. mean) squared Summation of (x- sample mean) squared
Sum of squares (ss)
SS divided by N
ss divided by N-1
variance
square root of variance squared
standard deviation
X - pop mean divided by variance
X - sample mean divided by variance
z score of individuals
sample mean - population mean divided by (variance divided by square root of sample size)
z-score of means
Nominal
categorical
ordinal
rank order
interval
equal distance between measurements
rational
meaningful zero
Kurtosis
peakedness of the distribution
lepokurtosis
a lot of scores in the middle
platykurtosis
flat
When do you use the median?
- skewed/non normal
- undetermined values (SAT scores)
- open ended items (1,2,3, >4)
- ordinal
When do you use a bar graph?
Nominal (qualitative) (categorical)
when do you use a histogram?
interval or ratio (quantitative)
What effects variability?
- outliers
- sample size if really small
- stability under sampling
- open ended distributions
SS interpret
Summed squared distance from the mean
variance interpret
typical squared distance from the mean
Standard deviation interpret
typical distance between an individual score and an average score
sampling error
error between a sample statistic and the corresponding population parameter
distribution of sample means
set of means from all the possible random samples of a specific size selected from a specific population
expected value of M
the mean of the distribution of sample means, equal to the population mean
standard error of M
standard deviation of sample mean
variance(m) = variance/ square root of n