Class 29-37: Intro To Biostats Flashcards
How do researchers choose to accept or reject the null hypothesis?
Statistical analysis
Based on p and confidence intervals.
3 primary levels for variables based on answers:
Nominal
Ordinal
Interval
2 key attributes of data measurement:
Magnitude
Consistency of scale.
Each attribute can be assessed w/ a “yes” or “no” response to the inquiry of:
“Does it have it?”
No magnitude and no consistency
Dichotomous/binary and NON ranked
Simply labeled variables w/o quantitative characteristics (dichotomous)
Nominal
Has magnitude but no consistency of scale
Ranked categories
Pain scales, severity of disease
Ordinal
Has magnitude and consistency of scale
Anything drawn w/ exact values
Interval / ratio
Nominal and ordinal attributes are considered:
Interval attributes are considered:
Discrete; continuous
Which statistical tests are selected based on level of data being compared
ALL statistical tests
After data, is collected we can appropriate go _____ in specificity/detail of data measurement (levels), but we can never go _____
Down; up
Non-comparative. Simple description of various elements of the study’s data
Descriptive statistics.
Measures of central tendency and dispersion
Mode/ median/ mean
Outliers
Minimum / max /. Range
Interquartile range= Q3-Q1
Know how to calculate these b/c it will be free points on the test.
The average of the squared differences in each individual measurement value and the groups mean
Variance- from the mean
The larger the number= the more variable
Square root of variance value (restores units of mean)
Standard deviation (SD)
Normally distributed= (one word)
Symmetrical
What graph is found when mean / median / mode are equal or near-equal:
Normally distributed
Interval data must be:
Normally distributed.
Stats tests useful or _____________________ data are called parametric tests
Normally-distributed
SD in normal distribution:
68%-top of bell curve
95%= +2 SD
99.7%= +3 SD
Parametric tests
Fixed mean / median / mode
Positively skewed graph
Asymmetrical distribution w/ one tail longer than the other
A distribution is skewed anytime the median differs from the mean (when mean is higher than median.
Mean > median
Negatively skewed graph:
Asymmetrically distributed w. One tail loner than another to the left.
Distribution is skewed anytime the median differs from the mean (when mean is lower than median)
Mean < median
Mean = 15.15 Median= 3 Mode= 0
Mean > median
Positively skewed
Outliers do not change:
The mode