Chapter 1 Biostats

Data can be non-numerical but can always be ____________

Transformed into numbers

Statistics

The investigation and evaluation of data

4 possible sources of data

Records, Surveys, Experiments, and external sources

Variable

Characteristic that takes on different values in different situations

Quantitative

Based on numbers

Qualitative

Measured in categories

Random variable

A value that arises from chance factors, it cannot be predicted

Discrete random variable

Not continuous, has gaps in its measurements

Continuous random variable

Can assume any value in a given range

Nominal scale

Categorizing and/or naming observations into exhaustive categories

Ordinal scale

Ranked observations that can be assigned a number

Interval scale

Truly quantitative scale with a fixed unit of measurement and a zero or reference point

Ratio scale

Any value in a given interval may be measured

Example of Nominal scale

Employees over and under 50

Example of Ordinal scale

Survey asking people to rank their experience 1-3 (gaps between categories need not be even)

Example of Interval scale

Students in a class

Example of Ratio scale

Height, weight, and length

Statistical inference

Reaching a conclusion about a population based on info from a sample

Not all samples are ________

Created equal

Sampling with replacement

Every member of the population is available at each draw

Sampling without replacement

Those selected from the population are not placed back in

Systematic sampling

Random number is chosen as the starting point (x) and an interval is also chosen (k)

Formula for systematic sampling

x, x+k, x+2k, x+3k, …

Stratified random sampling

Partitions populations into groups, or strata then chooses a random sample from each strata

Example of Stratified random sampling

The burn center analogy

Steps of the scientific method

Question formulation, Hypothesize, Experiment, analysis, Conclusion