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Used to describe and synthesize data.
Descriptive statistics
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Examples of descriptive statistics
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A descriptive index from a sample.
statistic
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Research questions are about parameters, but researchers calculate statistics to estimate them and use _________ to make inferences about the population.
inferential statistics
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When averages and percentages are calculated from population data, they are called _____.
parameters
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The lowest leel of measurement.
Nominal
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The level of measurement that involves assigning numbers to classify characteristics into categories.
nominal
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Examples of variables amenable to nominal measurement.
- gender
- blood type
- marital status
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Level of measurement that involves sorting peope based on their relative ranking on an attribute.
Ordinal
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______ measurement captures info about not only equivalence, but also about relative RANK.
Ordinal
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A level of meaurement that, for example, uses coding for functional abilities.
Ordinal
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_______ measurement occurs when researchers can specify rank ordering on an attribute and can assume equivalent distance b/w them.
Interval
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The Fahrenheit temp scale is an example of this level of measurement.
Interval
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In _______ scales, there is no real, rational zero point; ________ scales DO have an absolute zero..
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Most psychological and educational tests yield ______ -level data.
interval
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A person's weight is measured on a ______ scale.
ratio
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_________ measures provide info abou the ordering on a critical attribute, the intervals b/w objects, AND the absolute magnitude of the attribute.
Ratio
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Because ratio scales have an absolute zero, all _______ ops are permissable.
arithmetic
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Averages are meaningless for which levels of measurement?
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Ranking people from lightest wt (1) to heaviest (6) is using a ________ scale.
ordinal
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Using _________ measures you would classify someone's weight as being either heavy (1) or light (2).
nominal
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_____ and ______ measures usually are discernible, but the distinction b/w _____ and ______measures is more problematic.
- nominal & ratio
- ordinal & interval
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A set of data can be described in what three characteristics?
- shape of distribution of values
- central tendency
- variability
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A systematic arrangement of values from lowest to highest, together with a count of the number of times each value was obtained.
frequency distribution
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The sum of the frequencies must equal the _______.
sample size
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Graphs for displaying ______ and _______ data include histograms and frequency polygons.
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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
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When the longer tail of a frequency polygon points to the RIGHT, the distribution is ________.
positively skewed.
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When the longer tail of a frequency polygon points to the LEFT, the distribution is ________.
Negatively skewed
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The normal distribution plays a key role in _________ statistics.
inferential
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The term average is used to designate __________.
central tendency
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The ____ is the most frequently occurring score value in a distribution.
mode
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The _____ is used primarily to describe typical values for nominal-level measures.
mode
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Mode also means ______.
"typical"
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The _______ is the point in a distribution above which and below which 50% of cases fall.
median
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The median does not take into account the quantitative values of scores; it is an index of the average _______ in a distribution.
position
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Median values are insensitive to _________.
extremes
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The _______ is often the preferred index of central tendency when a distribution is skewed.
median
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How do scores affect the mean and median?
The mean is affected by EVERY score; the median is not necessarily.
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When researchers wotk with _____ or ______-level measurements, which is usually the statistic reported?
the mean (not the median or mode)
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The _____ is the most stable index of central tendency.
mean
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The mode is most suitable for _______ measures.
nominal
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The mode or median is most suitable for _______ measures.
ordinal
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The mean is most suitable for _______ measures.
ratio
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How spread out or dispersed the data are.
variability
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Researchers compute an index of _________ to express the extent to which scores in a distribution differ from one another.
variability
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Two commmon indexes of variablity.
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The highest score minus the lowest score in a distribution.
range
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Three limitations of range.
- ignores variations in scores b/w 2 extremes
- unstable and fluctuates widely
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With interval- or ratio-level data, the most widely used measure of variability is?
the standard deviation
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The difference b/w an individual score and the mean.
Deviation score
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If a person weighs 150 lbs and the mean was 140, what would the deviation score be for that person?
+10
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The value of the standard deviation before a square root has been taken.
variance
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A larger SD means what about the sample?
it is more heterogenous
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What does the SD tell us?
how much, on average, scores deviate from the mean
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