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Biostatistics Exam 1/63 Questions with Accurate Answers
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Biostatistics Exam 1/63 Questions with Accurate Answers
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Biostatistics Exam 1/63 Questionswith Accurate Answers
box and whisker plot - - A graph that displays the highest and lowest limits
of data as whiskers, the middle two quarters of the data as a box, and the
median
- Percentile - - Assume that the elements in a data set are rank ordered
from smallest to largest. The values that divide a rank-ordered set of
elements into 100 equal parts.
- Quartiles - - Values that divide a data set into four equal parts
- Location parameter - - Descriptive measures (Mean and Median) that can
be used to designate certain positions on the horizontal axis when the
distribution of a variable is graphed.
- ordered array - - An ordered list of data from largest to smallest or vice
versa
- frequency distribution - - an arrangement of data that indicates how often
a particular score or observation occurs
- relative frequency distribution - - The proportion of values falling within a
class interval. Frequency/ total # of values.
- statistic - - a number that describes a sample
- Parameter - - a number that describes a population
- frequency polygon - - special kind of line graph that can portray a
frequency distribution.
- Histogram - - A graph of vertical bars representing the frequency
distribution of a set of data.
- arithmetic mean (average) - - The sum of all the values in the population/
sample divided by the number of values.
- Properties of the Mean - - 1) Uniqueness: for a given set of data there is
one and only one mean.
2) Simplicity: The arithmetic mean is easily understood and calculated.
3) Affected by each value: since each value in a set of data enters into the
computation of the mean. extreme values, therefore, have an influence on
, the mean in some cases can so distort it that it becomes as a measure of
central tendency.
- Median - - the middle score in a distribution; half the scores are above it
and half are below it
- Properties of a median - - 1) Uniqueness: there is only one median for a
given set of data.
2) Simplicity: easy to calculate.
3) Not affected by extreme values.
- Variance - - compares how each value is with respect to the mean.
- standard deviation - - the square root of the variance.
how much members of a group can vary from the mean.
- Skewness - - a measure of the degree to which a distribution is
asymmetrical
- degrees of freedom - - The number of individual scores that can vary
without changing the sample mean. Statistically written as 'N-1' where N
represents the number of subjects.
- coefficient of variation - - - Good for comparing the variation of 2 data
sets.
- independent of the unit of measurement.
- useful for comparing the variability of 2 or more variable measures on
different scales.
- What are the advantages and limitations of the range as a measure of
dispersion? - - advantage: calculation is simple.
disadvantage: poor measure of dispersion.
- Explain the rationale for using n-1 to compute the sample variance. - - the
usage of n-1 when calculating the sample variance is an unbiased and
reliable calculation. When taking a sample from a population with a
population mean of u(miu)= x, the sample will have a different mean
compared to the population. subtracting 1 will allow the values to be more
accurate when calculating the sample variance. n-1 is the degree of freedom
of the variance.
we are eliminating 1 d.o.f from the sample mean in order to accurately
represent the population mean u.
- What is the purpose of the coefficient of variation? - - it's useful for
comparing the variability of 2 or more variable measures on different scales.
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