BIOSTATS: Lecture 1 Notes
Statistics: a collection of methods for planning experiments, obtaining data, and
then organizing, summarizing, analyzing, interpreting, presenting, and drawing
conclusions based on data
Population: group of all individuals you are studying
Sample: some members of the population we select to measure
Census: the collection of data from every member of the population
Parameter: a measurement describing some characteristic of a population
Statistic: a measurement describing some characteristic of a sample
Types of Data –
Nominal
- Names, labels, categories (no order we can put them in)
- E.g. hair colour
Ordinal
- Categories that have an order to them (not numbers)
- Differences are meaningless between the data values
- E.g. stress levels
Interval
- Quantitative
- Like ordinal, but difference is meaningful (+ or -)
- No natural 0 starting point
- E.g. shoe size, temperature
Ratio
- Quantitative
- Ratios and differences are meaningful (x or /)
- Natural 0 starting point
- E.g. weight, age, distance
Bias: a systematic favoritism in the data selection process, resulting in misleading
results
- If you keep choosing randomly, it does not fix your problem
Confounding: occurs when effects of variables are somehow mixed so that the
individual effects of variables cannot be identified
Discrete data: number of possible values is either a finite or a “countable” number
Continuous data: infinitely many possible values that correspond to some
continuous scale that covers a range of values without gaps, interruptions, or jumps Block: a group of subjects that are known (prior to the experiment) to be similar in
the ways that might affect the outcome of the experiment
Statistical Studies –
Observational Study - observe and measure specific characteristics but we do
not attempt to modify the subjects being studied
o Cross-sectional study – data measured at one point in time
o Retrospective (or case-control) – go back in time to collect data
o Prospective (or cohort) study – go forward in time and observe
groups sharing common factors such as smokers and non-smokers
Experiment - apply some treatment and then proceed to observe its affects
on the subjects
o Key elements in design of experiments:
1. Control effects of variables through blinding blocks -

More
Less