Flashcards in MA 3110 STATS CHAPTER 1 Deck (33):

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## DATA

### Collections of observations such as measurements, genders, survey responses.

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## STATISTICS

### The science of planning studies and experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions based on the data.

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## POPULATION

### The complete collection of all individuals (scores, people, measurements, and so on) to be studied. The collection is complete in the sense that it includes all of the individuals to be studied.

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## CENSUS

### The collection of data from every member of the population.

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## SAMPLE

### A sub-collection of members selected from a population.

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## PARAMETER

### A numerical measurement describing some characteristic of a population.

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## STATISTIC

### A numerical measurement describing some characteristic of a sample.

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## DISCRETE DATA

### Results when the number of possible values is either a finite number or a "countable" number. (The number of possible values is 0 or 1 or 2, and so on.

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## CONTINUOUS (NUMERICAL) DATA

### Result from infinitely more possible values that correspond to some continuous scale that covers a range of values without gaps, interruptions, or jumps.

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## 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).

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## Quantitative (Numerical) data

### Consists of numbers representing counts or measurements.

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## Categorical (Qualitative or attribute) data

### Consist of names or labels that are not numbers representing counts or measurements.

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## Ordinal level of measurement

### If data can be arranged in some order, but difference (obtained by subtraction) between data values either cannot be determined or are meaningless.

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## Interval level of measurement

### Is like the ordinal level with the additional property that the difference between any two data values is meaningful. However, data at this level do not have a natural zero starting point (where none of the quantity is present).

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## Ratio level of measurement

### Is the level with the additional property that there is also a natural zero starting point (where zero indicates that none of the quantity is present). For values at this level, differences and ratios are both meaningful.

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## Voluntary response sample (or self-selected sample)

### One in which the respondents themselves decide whether to be included.

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## Observational study

### We observe and measure specific characteristics, but we don't attempt to modify the subjects being studied.

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## Experiment

### We apply some treatment and then proceed to observe its effects on the subjects.

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## Simple random sample

### Of n subjects is selected in such a way that every possible sample of the same size n has the chance of being chosen.

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## Random sample

### In this sample members from the population are selected in such a way that each individual member in the population has an equal chance of being selected.

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## Probability sample

### Involves selecting members from a population in such a way that each member of the population has a known (but not necessarily the same) chance of being selected.

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## Systematic sampling

### Select some starting point and then select every Kth (such as every 50th) element in the population

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## Convenience sampling

### We simply use results that are very easy to get.

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## Stratified sampling

### We 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 we draw a sample from each subgroup or stratum.

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## Cluster sampling

### We first divide the population area into sections (or clusters), then randomly select some of the those clusters, and then choose all the members from those selected clusters.

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## Cross-sectional study

### Data are observed, measured, and collected at one point in time.

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## Retrospective (Case control) study

### Data are collected from the past by going back in time (through examination of records interviews, and so on.)

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## Prospective (Longitudinal or cohort) study

### Data are collected in the future from groups sharing common factors (called cohorts).

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## Confounding

### Occurs in an experiment when you are not able to distinguish among the effects of different factors.

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## Sampling error

### The difference between a sample result and the true population result; such an error results from chance sample fluctuations.

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## Nonsampling error

### Occurs when the sample data are incorrectly collected, recorded, or analyzed ( such as by selecting a biased sample, using a defective measurement instrument, or copying the data incorrectly).

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## Spreadsheet

### A collection of data organized in an array of cells arranged in rows and columns, and is used to summarize, analyze, and perform calculations with the data

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