Chapter One- Introduction to Statistics Flashcards
What is data?
Data are collections of observations, such as measurements, genders, or survey responses.
What is datum?
A single data value
What is statistics?
Statistics is the science of planning studies and experiments; obtaining data; and then organizing, summarizing, presenting, analyzing, and interpreting those date and then drawing conclusions based on them.
What is a population?
A population is the complete collection of ALL measurements or data that are being considered.
What is a census?
A census is the collection of data from EVERY member of the population.
What is a sample?
A sample is a sub-collection of members from a population.
What is a parameter?
A parameter is a numerical measurement describing some characteristic of a population.
What is a statistic?
A statistic is a numerical measurement describing some characteristic of a sample.
What does Quantitative data consist of?
Quantitative data consist of numbers representing counts or measurements.
What does Categorical data consist of?
Categorical data consist of names or labels that are NOT numbers representing counts or measurements.
When does Discrete Data result?
Discrete Data result when the data values are quantitative and the number of values is finite or “countable”. (If there are infinitely many values, the collection of values is countable if it is possible to count them individually, such as the number of tosses of a coin before getting tails.
When does Continuous Data result?
Continuous Data result from infinitely many possible quantitative values, where the collection of values is not countable. (That is, it is impossible to count the individual items because at least some of them are on a continuous scale, such as the lengths from 0cm to 12cm.)
Define “ Nominal Level of Measurement”.
The Nominal Level of Measurement is characterized by data that consist of names, labels, or categories only. The data cannot be arranged in an ordering scheme (such as low to high).
Define “ Ordinal Level of Measurement”.
Data are at the Ordinal Level of Measurement if they can be arranged in some order, but differences (obtained by subtraction) between data values either cannot be determined or are meaningless.
Define “Interval Level of Measurement”.
Data are at the Interval Level of Measurement if they can be arranged in order, and differences between data values can be found and are meaningful. Data at this level do not have a natural zero starting point at which none of the quantity is present.
Define “ Ratio Level of Measurement”.
Data are at the Ratio Level of Measurement if they can be arranged in order, differences can be found and are meaningful, and there is a natural zero starting point (where zero indicates that NONE of the quantity is present). For data at this level, difference and ratios are both meaningful.
Define “Observational Study”.
In an observational study, we observe and measure specific characteristics, but we don’t attempt to modify the subjects being studied.
Define “Experimental Study”
In an experiment, we apply some treatment and then proceed to observe its effects on the subjects, (subjects in experiments are called experimental units)
What is “random sampling”?
Random Sampling is when each member of the population has an equal chance of being selected. Computers are often used to generate random telephone numbers.
What is “simple random sampling”?
Simple Random Sampling is when a sample of N subjects is selected in such a way that every possible sample of the same size N has the same chance of being chosen.
What is “systematic sampling”?
Systematic Sampling is when you select a starting point, then select every kth (such as every 50th) element in the population.
What is “convenience sampling”?
Convenience sampling is when you use results that are easy to get.
What is “stratified sampling”?
Stratified sampling is when you subdivide the population into at least two different subgroups (or strata) so that subjects within the same subgroup share the same characteristics) such as gender or age bracket), then draw a sample from each subgroup.
What is “cluster sampling”?
Cluster sampling is when you divide the population into sections (or clusters), then randomly select some of those clusters, and then choose ALL members from those selected clusters.