Zusammenfassung der Ressource
Statistics
- Population / population parameters
- Standard Error
Anmerkungen:
- Standard error from population
- population Mean
- population variance
- population Stand Dev
- Samples / Point Estimates
Anmerkungen:
- use sample statistic to estimate the population parameters.
Point estimates - single value that approximates the true value of a population parameter
- Mean x
- Variance
- Stand Dev S
- Hypothesis tests
Anmerkungen:
- Statistical hypothesis is a claim about a population parameter and determines what we actually test
- confidence interval
Anmerkungen:
- A range of likely values for a population parameter.
Using CI we can say: it is likely that the population parameter is somewhere within this range.
- confidence level 99%
Anmerkungen:
- how sure we are that confidence interval containts the actual population parameters
- confidence level 95%
- confidence level 90%
- practice
- compare to samples
- compare sample to industry std.
- Null H0
Anmerkungen:
- Population parameter equals a specified value or equals parameter from another population
- p-value
t-value
- NULL = FALSE
significant
difference
Anmerkungen:
- rejection = significant evidence of difference between mean from sample and population mean
- reject null
hypothesis
Anmerkungen:
- if we reject our results are statistically significant
- (NULL true) type 1 error
Anmerkungen:
- if null hypothesis is true and we reject it: type 1 error
- probability = alpha
Anmerkungen:
- reducing alpha increasing beta
- NULL false:
correct decision
- Power (1 - Beta)
- sample size
Anmerkungen:
- sample increases, power increases.
sample + ...... power +
- population differences
Anmerkungen:
- as the population diffrences decreases, power decreases as well
- variability
Anmerkungen:
- As variability increases, power decreases
- level Alpha
Anmerkungen:
- common 0.05 level mean that we are willing to accept a 5% chance that we incorrectly rejected the null hypothesis
if alpha is set higher we are more likely to correctly reject the null hypothesis
if alpha has smoller value is easier to see difference between sample mean and population mean
- NULL = TRUE no
difference evidence
Anmerkungen:
- there is no evidence for difference between sample mean and population mean
- fail to reject the null
hypothesis
Anmerkungen:
- it concludes that we have not enough evidence to claim that alternative hypothesis is true
- type 2 error
Anmerkungen:
- if null hypothesis is false and we fail to reject it: type 2 error
- probability = Beta
Anmerkungen:
- increasing beta reducing alpha
- NULL true :
correct
decision
- Alternative H1
Anmerkungen:
- Population parameter does not equal specified value
- making decision
- 1-sample t-test
Anmerkungen:
- determine whether the population mean is equal to a hypothesized value
- Numeric data
- Random Data
- hypothesed value = population mean
- procedure
- determine null
Anmerkungen:
- the null hypothesis is that the hyphotesiszed value is equal to population mean
- determine alternative
Anmerkungen:
- alternative is the opposite null
- collect sample from population
- sample mean
- sample
standard
deviation
- Graph
Anmerkungen:
- graph to take a sense of variability and information about the mean
- individual value plot
- interpret
- p-value
- T-value
- alpha level
- 2
variance
test
- Numeric Data
- Random Data
- comparing
two
populations
- procedure
- determine NULL
Anmerkungen:
- null hypothesis state that two populations have the same variability
- determine alternative
Anmerkungen:
- there is not the same variance between two populations
- colect sample 2 population
- data continious
- cmes from 2
independet
samples
- randomly taken
- graph data
- interpret test
- Bonett
- Leven
- 2 sample t-test
- procedure
- termine NULL
- determiane alternative
- collect samples
- Normally distributed
- randomly taken
- taken from 2
populations
- ndependent samples
- potentially unequal variationces
- probalility plot ?
- graph the data
- two
individual
value plot
- conduct
test,
interpret
data
- p-value
- Paired t-test
- procedure
- NULL hypothesis
Anmerkungen:
- the population means are equal
- alternative hypothe
Anmerkungen:
- the population means are not equal
- collect paired samples
- Probability test required?
Anmerkungen:
- do we need to prove probability ? Are we sure that data are with normal distribution?
- dependent sample
- numeric
- random sample
- normally distributed
- graph the data
Anmerkungen:
- Individual value plot (values are substracted between both samples.
We plot differences !
- conduct test interpretation
Anmerkungen:
- checking p-value, t-value and confidence interval. how calculated mean relate to confidence interval?
- Normal Distribution
- 1Sigma
- 2 sigma
- 3 sigma
- Estimated Standard Error
Anmerkungen:
- calculate sampling deviation
- Z-score
Anmerkungen:
- t-disctribution
Anmerkungen:
- t-distribution applied to sampling and used only for normal distribution data
- Cumulative probability
Anmerkungen:
- cumulative probability for a single observation
- Descriptive Statistics
- Bar Chart
Anmerkungen:
- Compare categorical data, display counts of several categories, shows the frequency of each categories, easy to spot differences between two or more groups in count,
- Pareto Chart
Anmerkungen:
- Produced to identify the largest opportunities for improvements
- Pie Chart
Anmerkungen:
- Shows relation of parts to a whole, shows differences in percentage between
categories in group or groups, (proportions of each categories relative to the
whole),
- Histogram
Anmerkungen:
- Shows
the distribution of the data set, shape of the distribution, symmetricity, numerate to large number of displayed data
- Dotplot
Anmerkungen:
- Dotplot,
displays dot for each data value in the bin, useful for small set of numeric data, we can see how the data
is clustered (density in the bin), and shows the outliers
- Individual Value Plot
Anmerkungen:
-
Displays individual
variables for single group or groups of variables, (for example data for two production lines)
The individual value plot is graph with one dot representing each individual value.
- Boxplot
Anmerkungen:
- Help to see larger
patterns in the set distribution,
Summarize the
distribution of data, Shows distribution
of data, can be used to compare distribution of two groups (for example morning
and evening shifts)
- Time Series Plot
Anmerkungen:
- Shows
patterns over time, (increasing or decreasing variation over time), time
related questions about variable, change in the process in the time scale or
change in the data collection, variation over time is consistent?,