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Used to describe and synthesize data.
Descriptive statistics

Examples of descriptive statistics

A descriptive index from a sample.
statistic

Research questions are about parameters, but researchers calculate statistics to estimate them and use _________ to make inferences about the population.
inferential statistics

When averages and percentages are calculated from population data, they are called _____.
parameters

The lowest leel of measurement.
Nominal

The level of measurement that involves assigning numbers to classify characteristics into categories.
nominal

Examples of variables amenable to nominal measurement.
 gender
 blood type
 marital status

Level of measurement that involves sorting peope based on their relative ranking on an attribute.
Ordinal

______ measurement captures info about not only equivalence, but also about relative RANK.
Ordinal

A level of meaurement that, for example, uses coding for functional abilities.
Ordinal

_______ measurement occurs when researchers can specify rank ordering on an attribute and can assume equivalent distance b/w them.
Interval

The Fahrenheit temp scale is an example of this level of measurement.
Interval

In _______ scales, there is no real, rational zero point; ________ scales DO have an absolute zero..

Most psychological and educational tests yield ______ level data.
interval

A person's weight is measured on a ______ scale.
ratio

_________ measures provide info abou the ordering on a critical attribute, the intervals b/w objects, AND the absolute magnitude of the attribute.
Ratio

Because ratio scales have an absolute zero, all _______ ops are permissable.
arithmetic

Averages are meaningless for which levels of measurement?

Ranking people from lightest wt (1) to heaviest (6) is using a ________ scale.
ordinal

Using _________ measures you would classify someone's weight as being either heavy (1) or light (2).
nominal

_____ and ______ measures usually are discernible, but the distinction b/w _____ and ______measures is more problematic.
 nominal & ratio
 ordinal & interval

A set of data can be described in what three characteristics?
 shape of distribution of values
 central tendency
 variability

A systematic arrangement of values from lowest to highest, together with a count of the number of times each value was obtained.
frequency distribution

The sum of the frequencies must equal the _______.
sample size

Graphs for displaying ______ and _______ data include histograms and frequency polygons.

How are histograms and frequency polygons different?
 Histogram: bars are drawn above the score classes to the ht corresponding to the frequency of that score
 Frequency polygons use DOTS connected by straight lines to show frequencies

When the longer tail of a frequency polygon points to the RIGHT, the distribution is ________.
positively skewed.

When the longer tail of a frequency polygon points to the LEFT, the distribution is ________.
Negatively skewed

The normal distribution plays a key role in _________ statistics.
inferential

The term average is used to designate __________.
central tendency

The ____ is the most frequently occurring score value in a distribution.
mode

The _____ is used primarily to describe typical values for nominallevel measures.
mode

Mode also means ______.
"typical"

The _______ is the point in a distribution above which and below which 50% of cases fall.
median

The median does not take into account the quantitative values of scores; it is an index of the average _______ in a distribution.
position

Median values are insensitive to _________.
extremes

The _______ is often the preferred index of central tendency when a distribution is skewed.
median

How do scores affect the mean and median?
The mean is affected by EVERY score; the median is not necessarily.

When researchers wotk with _____ or ______level measurements, which is usually the statistic reported?
the mean (not the median or mode)

The _____ is the most stable index of central tendency.
mean

The mode is most suitable for _______ measures.
nominal

The mode or median is most suitable for _______ measures.
ordinal

The mean is most suitable for _______ measures.
ratio

How spread out or dispersed the data are.
variability

Researchers compute an index of _________ to express the extent to which scores in a distribution differ from one another.
variability

Two commmon indexes of variablity.

The highest score minus the lowest score in a distribution.
range

Three limitations of range.
 ignores variations in scores b/w 2 extremes
 unstable and fluctuates widely

With interval or ratiolevel data, the most widely used measure of variability is?
the standard deviation

The difference b/w an individual score and the mean.
Deviation score

If a person weighs 150 lbs and the mean was 140, what would the deviation score be for that person?
+10

The value of the standard deviation before a square root has been taken.
variance

A larger SD means what about the sample?
it is more heterogenous

What does the SD tell us?
how much, on average, scores deviate from the mean

