Biostatistics Flashcards
estimation and hypothesis testing are what type of statistics?
inferential
what is the purpose of inferential statistics?
make generalizations about population characteristics from incomplete data
definition: parameters
measurements based on population statistics (eg mean)
definition: statistic
measurements based on a sample
definition: categorical variable
numeric or character codes that represent either
- presence or absence of something that is of research interest
- the relative weight or rank of the thing that is of research interest
definition: process
- series of actions or operations that transforms inputs to outputs
- produces or generates output over time
definition: nominal scale
categories without order
definition: ordinal scale
nominal variables with an inherent order among the categories (ex stage 1, 2, 3 for cancer)
how can qualitative variables be presented?
- summary table
- bar graph
- pie chart
how can quantitative variables be presented?
- dot plot
- stem and leaf
- frequency distribution
- histogram
what are the two characteristics of numerical summary?
- central tendency
2. variability
what is the symbol for mean of a sample?
X bar
what is the symbol for mean of a population?
u
what is the symbol for size of a sample?
n
what is the symbol for size of a population?
N
if the mean is greater than the median what is the skew?
right skew
if the mean is less than the median what is the skew?
left skew
x + s contains what % of measurements?
68%
x + 2s contains what % of measurements?
95%
x + 3s contains what % of measurements?
99.7%
what does a z score describe? what does it measure?
- relative location of a measurement compared to the rest of the data
- measures the number of standard deviations away from the mean a data value is located
what % of of measurements have a z score between -1 and 1? -2 and 2? -3 and 3?
- 68%
- 95%
- 99.7%
