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What is statistics?
a branch of mathematics that provides techniques to analyze whether or not your data is significant (meaningful)
Statistical applications are based on probability statements
Nothing is “proved” with statistics
Statistics are reported
Statistics report the probability that similar results would occur if you repeated the experiment
Statistics deals with numbers
Need to know nature of numbers collected
–Continuous variables: type of numbers associated with measuring or weighing; any value in a continuous interval of measurement.
–Weight of students, height of plants, time to flowering
–Discrete variables: type of numbers that are counted or categorical
–Numbers of boys, girls, insects, plants
Can you figure out…
Which type of numbers (discrete or continuous?)
–Numbers of persons preferring Brand X in 5 different towns
–The weights of high school seniors
–The lengths of oak leaves
–The number of seeds germinating
–۳۵ tall and 12 dwarf pea plants
–Answers: all are discrete except the 2nd and 3rd examples are continuous.
Populations and Samples
Population includes all members of a group
–Example: all 9th grade students in America
–Number of 9th grade students at SR
–No absolute number
–Used to make inferences about large populations
–Samples are a selection of the population
–Example: 6th period Accelerated Biology
Why the need for statistics?
–Statistics are used to describe sample populations as estimators of the corresponding population
–Many times, finding complete information about a population is costly and time consuming. We can use samples to represent a population.