Business Statistics
Omkar & Yaying
Wednesday 5-6pm
WEEK 3 BES PASS
Descriptive Statistics Population - a set of all possible observations. Sample - a portion of a population. We often use information concerning a sample to make an inference (conclusion) about the population.
Parameter - describes a characteristic of the population, eg: the population variance Statistic- describes a characteristic of a sample, eg: the sample variance
Frequency Distribution and Histograms Class - a collection of data which are mutually exclusive Frequency distribution - a grouping of data into classes Relative frequency distribution - calculates the number of data in a class as a percentage of the total data
Shapes of Distributions and Histograms
A histogram is symmetrical if one half of the histogram is a mirror reflection of the other Non-symmetrical distributions are said to be “skewed”
a) Skewed to the right (Positively skewed) Mode < Median < Mean
b) Skewed to the left (Negatively skewed) Mode > Median > Mean
c) Symmetric Distribution Mode = Median = Mean
Measures of Central Tendency: The Mean, Mode and Median The mean is the average of scores: Population mean: μ = Σ xi/N
Sample mean: x = Σ xi/n
The mode is the value that has the highest frequency The median is the middle value of data ordered from lowest to highest The median and the mode are relatively less sensitive to outliers.
Quartiles and Percentiles, including the Median Percentile values divide the data (arranged in ascending order) into 100 equal parts.
They are a measure of relative standing. P% of the data is less than the pth percentile, and (100 – p)% of the data is greater than the pth percentile.
BES PASS S1 10
1
Omkar & Yaying
Wednesday 5-6pm
L= The median is the 50th percentile
p x (n + 1) 100
The inter-quartile range is the difference between the 75 th percentile (upper quartile) and the 25th percentile (lower quartile) E.g. o o o 2,
Wednesday 5-6pm
WEEK 3 BES PASS
Descriptive Statistics Population - a set of all possible observations. Sample - a portion of a population. We often use information concerning a sample to make an inference (conclusion) about the population.
Parameter - describes a characteristic of the population, eg: the population variance Statistic- describes a characteristic of a sample, eg: the sample variance
Frequency Distribution and Histograms Class - a collection of data which are mutually exclusive Frequency distribution - a grouping of data into classes Relative frequency distribution - calculates the number of data in a class as a percentage of the total data
Shapes of Distributions and Histograms
A histogram is symmetrical if one half of the histogram is a mirror reflection of the other Non-symmetrical distributions are said to be “skewed”
a) Skewed to the right (Positively skewed) Mode < Median < Mean
b) Skewed to the left (Negatively skewed) Mode > Median > Mean
c) Symmetric Distribution Mode = Median = Mean
Measures of Central Tendency: The Mean, Mode and Median The mean is the average of scores: Population mean: μ = Σ xi/N
Sample mean: x = Σ xi/n
The mode is the value that has the highest frequency The median is the middle value of data ordered from lowest to highest The median and the mode are relatively less sensitive to outliers.
Quartiles and Percentiles, including the Median Percentile values divide the data (arranged in ascending order) into 100 equal parts.
They are a measure of relative standing. P% of the data is less than the pth percentile, and (100 – p)% of the data is greater than the pth percentile.
BES PASS S1 10
1
Omkar & Yaying
Wednesday 5-6pm
L= The median is the 50th percentile
p x (n + 1) 100
The inter-quartile range is the difference between the 75 th percentile (upper quartile) and the 25th percentile (lower quartile) E.g. o o o 2,