STA6166 F05-2 Sampling

STA6166 F05-2 Sampling - Topic (2) Sampling and...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Topic (2) – Sampling and Experimental Design 2-1 Topic (2) – Sampling and Experimental Design Some Definitions Experimental (or Sampling) Unit is the object or event from which the measurements are taken e.g. tree where the number of leaves is measured leaf where the weight is measured acre of land where the number of trees is measured hurricane where maximum inches of rain/hour is recorded year where the number of hurricanes of class 4 is recorded A Variable is the information recorded on an experimental unit e.g. Y = number leaves/tree Y = weight of leaf Y = number of trees/acre Y = max inches of rain/hour for a hurricane Y = number of hurricanes of class 4/ year NOTE: There can be several variables measured at once on the same experimental unit
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Topic (2) – Sampling and Experimental Design 2-2 e.g. number of leaves on the tree, the diameter at breast height of the tree, the species, etc. Categorical Variables are variables that can only take on values that are non-numeric categories or groups. The set of possible values should be mutually exclusive and exhaustive. Mathematical operations cannot be performed on categorical variables even if coded with numbers. e.g. color of a rose make of a car ethnic group species of tree name Quantitative Variables are numeric in value and hence have meaning as a measurement or quantity. Further, arithmetic operations can be performed on quantitative variables. e.g. number of car accidents on campus in July length of an antenna weight of a book kilowatts used in an hour number of segments in the abdomen of a arthropod
Background image of page 2
Topic (2) – Sampling and Experimental Design 2-3 1) Discrete Variable – quantitative variable which can take on only certain values number of car accidents on campus in July number of segments in the abdomen of a arthropod size class of a fish when recorded to the nearest 5 cm 2) Continuous Variable – quantitative variable which can take on any value in one or more intervals length of an antenna weight of a book kilowatts used in an hour Population: the complete set of values of one or more variables that could be measured on the entire set of experimental units under study. The definition of population depends on the particular research problem under study and on the method of sampling from that population. Sample: the set of values of one or more variables that were measured on a subset of the population of interest.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Topic (2) – Sampling and Experimental Design 2-4 EXAMPLE Research problem : effect of a drug on blood plasma cholesterol level in people who present at the doctor’s office with high levels Population : the cholesterol levels before and after drug treatment of individuals who 1) have high cholesterol levels and 2) could be picked for the study Sample: the before and after blood plasma cholesterol levels of the 100 people selected to participate in the study EXAMPLE Research problem : effect of a herbicide on corn yields in 100 m 2 plots Population: set of corn yields for all 100 m
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/23/2011 for the course STA 6166 taught by Professor Staff during the Summer '08 term at University of Florida.

Page1 / 25

STA6166 F05-2 Sampling - Topic (2) Sampling and...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online