Times Series and Trends Notes
Time series represents a variable observed across time.
Components of a Time Series
Trend (TR)
Seasonal variation (S)
Cyclical variation (C)
Irregular activity (I)
Trend
Trend is a steady increase or decrease in the time seri
Strategic Management Mid-Term Review
Module 1
What do we mean by a companys strategy?
A companys strategy is its action plan for outperforming its competitors and
achieving superior profitability. These includes:
- How to attract and please customers
- Ho
Forecasting Exponential Smoothing Notes
Exponentially Smoothed Forecasts
Assumes the trend and seasonal component are relatively
insignificant
Exponentially smoothed forecast is constant for all future values
Ft+1 = Et
Ft+2 = Ft+1
Ft+3 = Ft+1
Use for shor
Descriptive Analysis Exponential Smoothing Notes
Exponential Smoothing
Type of weighted average
Removes rapid fluctuations in time series (less sensitive to short
term changes in prices)
Allows overall trend to be identified
Used for forecasting future va
Forecasting Trend Simple Linear Regression Notes
Simple Linear Regression
Model: E(Yt) = 0 + 1t
Relates time series, Yt, to time, t
Cautions
Risky to extrapolate (forecast beyond observed data)
Does not account for cyclical effects
Seasonal Regression Mod
Elements of a Hypothesis Test Notes
Test Statistic - Difference between the Sample means, scaled to
number of standard deviations (standard errors) from the null
difference of 0 for the Population means:
Rejection Region - Set of values of the test statis
Key Ideas Strategic Management Notes
Time Series Data: Data generated by processes over time.
Index Number
Measures the change in a variable over time relative to a base period.
Types of Index numbers:
1. Simple index number
2. Simple composite index numb
Measuring Forecast Accuracy MAD and RMSE Notes
Mean Absolute Deviation
Mean absolute difference between the forecast and actual values of
the time series
where m = number of forecasts used
Mean Absolute Percentage Error
Mean of the absolute percentage of
Paasche Index Notes
Paasche Index
Uses quantities for each period as weights
Appropriate when quantities change over time
Compare current prices to base period prices at current purchase
levels
Disadvantages
Must know purchase quantities for each time per
DurbinWatson d-Test for Autocorrelation Notes
DurbinWatson d-Test for Autocorrelation
One-tailed Test
H0: No firstorder autocorrelation of residuals
Ha: Positive firstorder autocorrelation of residuals
(or Ha: Negative firstorder autocorrelation)
Test Sta
Seasonality and Cyclical Variation Notes
Seasonality
Seasonal variation refers to periodic increases or decreases that occur
within a calendar year in a time series. The key is that these movements in
the time series follow the same pattern each year.
Cyc
Interpolation and Extrapolation Notes
Interpolation is a way of determining variables on a graph within the given
data
Extrapolation is a way of determining variables on a graph outside the
given data
If I wanted to figure out how much snow would fall in
Hypothesis Testing Notes
Goal: Make statement(s) regarding unknown population parameter
values based on sample data
Elements of a hypothesis test:
Null hypothesis - Statement regarding the value(s) of
unknown parameter(s). Typically will imply no associat
Confidence Intervals Notes
Normally Distributed data - approximately 95% of individual
measurements lie within 2 standard deviations of the mean
Difference between 2 sample means is approximately normally
distributed in large samples (regardless of shape
Assignment 3
Ian Parina
John Ford
Strategic Management
1. What are the chief elements of Apples overall competitive strategy? How well do the pieces
fit together? Is the strategy evolving?
The chief elements of Apples overall competitive strategy are prod