Scholarship Time Series

Scholarship Statistics Study!

reliability of predictions depends on ________ within data, and if it is ________ or ________

variability, constant, changing

1. the ________ component is the long-term tendency, using ________ values of time series

trend, smoothed

a trend may be better analysed using a ________ model if there are two distinct sections

piecewise

2. the ________ component is longer-term variations that repeat over time, such as recessions or inflation

cyclical

3. the ________ component is repeating variations due to periodic influences

seasonal

a/an ________ seasonal effect is the difference between a raw value and smoothed value for that season

individual

a/an ________ seasonal effect is the smoothed value for all the individual seasonal effects

average

a ________ ________ value is a raw value with the average seasonal effect subtracted (also deseasonalised data value)

seasonally adjusted

4. the ________ component is erratic or residual variations not accounted for by the time series model (trend, cycle, seasonal components)

irregular

the irregular component is also known as ________

noise

the irregular component can be analysed by calculating the ________, the ________ between the individual seasonal effect and the average seasonal effect

residual, difference

the ________ ________ ________ model is a seasonal decomposition function used to show the:

• original series, or ________ data

• the ________ component

• the t________ and c________

• the ________, or random component

seasonal trend lowess, raw, seasonal, trend, cycle, residual

the main source of ________ for a time series plot can be determined by finding expressing the ________ of each of the trend, seasonal and residual components as a % of the range of ________ data

variation, range, raw

the Holt-Winters ________ Model assumes that the seasonal pattern is ________

Additive, consistent

the Holt-Winters ________ Model can be used instead if the seasonal patterns are ________ or if there is a significant ________ component

Multiplicative, inconsistent, cyclical

forecasts weigh ________ data more heavily

recent

forecasts use ________ of data to create predictions

smoothing

________ are predictions made beyond the time intervals recorded within the data set

extrapolations

forecasts are less ________ the further they are extrapolated

reliable

forecasts may be ________ due to unforeseen changes such as environmental disasters or major economical or political changes

incorrect

a/an ________ number shows the value of a quantity relative to its value at a chosen period, to take into account ________ (where the purchasing power of $ decreases)

index, inflation

a value for a particular time period can be deflated by calculating:

$ x (index of ________ period) / (index of ________ period)

base, time

a time series report should be based on the PPDAC statistical enquiry cycle:

• P________

• P________

• D________

• A________

• C________

problem, plan, data, analysis, conclusion

suggest improvements to minimise potential sources of ________ and to increase the ________ of the predictive model

bias, accuracy

discuss the ________ of the analysis

limitations

formulate and define the ________ in the form of a ________ ________. the ________ should answer this, using justification from the ________. any areas of uncertainty should be highlighted, as well as suggesting related questions to further areas of study

problem, statistical question, conclusion, analysis

statistical question: "what has been the ________ in the price of a 375g jar of peanut butter in New Zealand stores over the ________ 12 years, and can this data be used to inform a ________ of future prices?"

trend, past, forecast