Flashcards in Book - Chapter 8 Analytical Theory Time Series Deck (21)

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1

## What does timeseries mean

### Ordered sequence of equally spaced values over time

2

## What does timeseries analysis mean

### Accounts For the internal structure of observations taken over time

3

## What are the goals of timeseries analysis

### To identify the internal structure of the time series. To forecast future events

4

## What is the box Jenkins method

### A RMA. Autoregressive moving averages

5

## What does the box Jenkins method do

### Models historical behaviour to forecast the future

6

## What would you use box Jenkins Method /ARMA to do

### Forecast. For example, next months sales, tomorrow’s stock price, hourly power demand

7

## What three components do you need to model a timeseries

### The trend term. The seasonal term. The random component

8

## What does box Jenkins methodology assume

### The random component is a stationary sequence

9

## What makes a stationary sequence

### Constant mean. Constant variance. Autocorrelation does not change over time

10

## To obtain a stationary sequence what must the data be

### Detrended and seasonally adjusted

11

## How would you remove a simple linear trend

### By subtracting a least squares fit straight line

12

## ARMA model is also known as

### The P, Q model

13

## ARIMA as what to the ARMA model

### Adds a difference in time

14

## In Arima what does it mean

### Autoaggressive intra dated moving average. It includes the detrending as part of the model

15

## what is ARIMA also known as

### The p d q model.

16

## The Arima model, Multiple models need to be built in compared using

### ACF and PACF

17

## What is ACF

### Autocorrelation function. Correlation of the values of the timeseries with itself. It helps to determine the order, Q, of a MA model

18

## What is PACF

### Partial autocorrelation function. And autocorrelation calculated after removing the linear dependence of the previous terms. Helps to determine the order, P, of a AR model

19

## What is the quantity H in ACF referred to as

### Lag

20

## What is the white noise process

### The Eire term and is used to represent random, independent fluctuations that are part of the timeseries

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