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Statistics final wgu academy 2024/2025(100% verified) A+ score assured

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  • March 27, 2024
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Statistics final wgu academy

nominal variables - ANSCategorical variables that there is no natural order among the
categories

ordinal variable - ANSCategorical variables where there is natural order among the
categories (low-high)

interval - ANSA measurement which makes sense to talk about the difference between
values but not the ratio between values

ratio - ANSQuantitive variables where is makes sense to talk about the difference in ratios.
(Income, weight)

In ratios: - ANSValue 0 means the absence of quantity (income $0)

Distribution of a Variable - ANSTells us what values the variables take and how often they
take those values

In intervals: - ANSVale 0 does not mean the absence of value (temp = 0F)

Pie charts - ANSEmphasize how the different categories relate to the whole

Bar charts - ANSEmphasize how the different categories compare with each other

Histogram - ANSBreaking the range of values into intervals and count how many
observations fall into interval.

Stemplot(stem and leaf plot) - ANSGraphical display of quantitive data. Data is spread into
"stem" and "leaf". It retains the data and sorts.

Boxplot - ANSGraphically represents the distribution of a quantitive variable. Visually
displays the five number summary and the observations classified as a suspected outlier.

Measures of Center - ANSMode, mean, and median.

Mode - ANSThe most commonly occurring value. Can be unimodal or bimodal

Mean - ANSThe average of a set of observations.
The sum of observations divided by the number of observations. (x bar)

Median - ANSThe midpoint of the distribution. (M)

Measures of soread - ANSRange, inter quartile range (IQR), standard deviation

, How to find the median - ANS-order the data smallest to largest
-if the number(n) of observations is odd (n+1)/2nd spot
-if the number(n) of observations is even we have two n/2 = spot & n/2 + 1 = spot

Measure of center that is sensitive to outliers - ANSMean

Measure of center that is not sensitive to outliers - ANSMedian

Symmetric distributions - ANSMean and median will be approximately equal

skewed right - ANSMean will be greater than the median

skewed left - ANSMean will be less than the median

range - ANSThe exact distance between the smallest data point and the largest. The most
intuitive measure of variability.

Inter-Quartile Range (IQR) - ANSMeasures the variability of a distribution by giving us the
range covered by the MIDDLE 50% of the data.
- Step 1: Arrange the data in increasing order, and find the median
- Step 2: Find the median of the lower 50% of the data = 1st quartile (Q1)
- Step 3: Repeat this again for the top 50% of the data = 3rd quartile (Q3)
- Step 4: The middle 50% of the data falls between Q1 and Q3. Therefore: IQR = Q3 - Q1

Note: When finding the median of an odd number of data items, it is not included in either
the bottom or top half of the data; when median is even, the data are naturally divided into
two halves.

When should the IQR be used? - ANSOnly when the median is used as a measure of center.

When should an outlier be kept in the data? - ANS-when the outlier is produced by the same
sort of physical or biological process as the rest of the data.
-the outlier is expected to eventually occur again

five number summary - ANSmin, Q1, median, Q3, max

standard deviation - ANSQuantifies the spread of a distribution by measuring how far the
observations are from their mean. ( gives the average distance between a data point and the
mean (xbar)

how to find standard deviation? - ANS-find the mean
-find deviations from the mean (xbar - 2,3,4,5 etc)
-square each deviation
-add all squared deviations then divide them by n - 1 (sample size minus 1)
-find square root of new total, this is the standard deviation

Variance of data - ANSThe average of the squared deviations

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