x’ forecast only on HP-32E

[C.Ret]

(06-20-2023 09:12 PM)brouhaha Wrote:  

(06-20-2023 12:56 PM)Dave Britten Wrote:  I always thought it was kind of odd they included it on the 12C but not the 11C or 15C.

"Life is short and ROM is full."
- Bill Wickes

But also there aren't extra key assignments available on the 11C and 15C.

Hi,

I like this quote but wouldn't it be from Wiliam C Wickes? Was Bill a joke-nickname?

Otherwise, the HP-15C actually lacks keys to put the two estimation x^ and y^ (not to be confuse with any forecast - only linear estimation link to the actual linear regression).


With the statistic accumulated in the HP-15C registers, both estimated values for x and y, denoted x^and y^, can be calculated without any program or any register substitution:

An estimated value for x (denoted x^) can be obtained from the sequence:

1. Press f ( L.R. )
2. Key in the know y-value
3. Press (X↔Y) ( - ) (X↔Y) ( ÷ )

An estimated value for y (denoted y^) can be obtained from one of the sequences:

1. Press f ( L.R. )(X↔Y)
2. Key in the know x-value
3. Press ( × ) ( + )

Alternatively

1. Key in the know x-value
2. Press f ( y^.r )

« Le statisticien est un homme qui fait un calcul juste en partant de prémices douteuses pour aboutir à un résultat faux. »
Jean Delacour
"The statistician is a person who performs accurate calculations based on approximate and debatable data, ultimately leading to an incorrect result."
Dubious Personal Translation.

Unlike forecasts, estimates don't have to worry about all those pesky things like data consistency, biases, measurement errors, distributions or dispersions shapes, theoretical vs empirical laws, probabilities, linearity...

Facts are stubborn, but statistics are more pliable.
Mark Twain