Tipos de vacunas

KEY

VP : A1 = -0.09 , B2 = +0.11 COLO): A1 = +0.05 , B2 = +0.11 C0L(2): A1 = 0 , B2 = +0.11

April-June and strengthening of the franc (weakening of the dollar) in July-September. This corresponds closely to the pound-dollar pattern with the dollar tending to strengthen and then weaken in the April-August period (Fig. 5.2). Furthermore the size of the seasonal variation in the franc-dollar rate (- 2 , 2 % - - 3» 2 % ) is of a similar

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order to that of the pound-dollar rate (- 2.*+%) and to a leaser extent that of the pound-franc rate (- 3 . 9 % ) .

Fewer speculative dummies were significant than in the pound- dollar and pound-franc estimates but all that were significant were correctly signed. A further difference relates to the tendency for smaller coefficients in the WP version than in the COL version (with the exception of F5 and S7). The performance of the American dummies was broadly consistent both with expectations and their performance in the pound-dollar estimates. S1, representing the flight of gold from the U.S. to the gold bloc in November, 1931» rather surprisingly fails to show up, and it must be assumed that official resistence (through intervention not picked up by the ID) prevented the implica­ tions of the gold movement from affecting the course of the exchange

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rate. S2, which was only significant at low levels in the pound- dollar equation, is insignificant here. This is less unexpected than the failure of S3 which was significant in the latter. However, the interregnum period (between Roosevelt's election and taking office) was one of conflicting influences, and it may be that, as far as the franc-dollar exchange rate is concerned, they cancelled each other out.

S k and S5 represent the 1933-3*+ period of dollar undervaluation

and perform as expected indicating that the undervaluation was greater in 193*+ (following the U.S. gold buying policy) them in 1933» They further suggest, in conjunction with earlier results, that the under-

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would be associated with dollar strength due to the uncertainties caused by the impending gold clause judgement in early 1935» but it was, in fact, significant and wrongly signed in the pound-dollar estimates indicating dollar weakness; this was interpreted as suggesting a continued undervaluation of the dollar into 1935 and it may have been that in the determination of the franc-dollar exchange rate these two offsetting influences cancelled each other out thereby causing S6 to be insignificant. S7 and S9 are correctly signed and significant (albeit the latter at rather low levels) and, although S8 was excluded, because it corresponded exactly with two French dummies of the same expected sign (FIO and F11) their signifi­ cance may be at least partly attributed to the influence represented by S8. S10 is insignificant as it was in the final estimates of the pound-dollar exchange rate.

The significant French speculative dummies are all correctly signed but there is some conflict with their performance in the pound- franc estimates where this was not the case. F1, F2 and F k were

insignificant in the estimates of both exchange rates. Four variables - F3, F6, F7 and F8 - which were significant in the pound-franc estimates were not significant here. This is a little surprising but it may reflect a tendency for events in France to have more impact (in terms of effects in confidence) in Europe than in America although this contention is somewhat undermined by the significance of F12 which was insignificant in the pound-franc estimates. However, this is not necessarily the case since the "Blum experiment" (and the dummies associated with it) do seem to be a plausible exception to the suggested rule that incidents in France may have influenced European opinion more strongly. Another exception is the Laval

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d e f la t io n (F 5 ) w h ic h seems to have created equal pessimism about the fra n c on b o th sid e s o f the A t l a n t i c .

The fo u r "Blum dummies" (F8 , F9, F10 and F11) were s i g n i f i c a n t and w ro ngly sig n e d in the p o u n d -fra n c estim a tes but in the d o l l a r - franc estim a te s th re e o f them are s ig n if ic a n t and c o r r e c t ly s ig n e d . At f i r s t s ig h t , t h e r e f o r e , the "Blum experim en t" seems p a r a d o x ic a lly to have caused th e fra n c to stre n g the n a g a in s t the pound but weaken

a g a in st the d o l l a r . T h is i s not an im p o s sib le sc e n a rio but would

seem an u n lik e ly one; f o r t u n a t e ly , a more p la u s ib le a lt e r n a t iv e e x p la n a tio n i s a v a ila b le when the fo u r v a r ia b le s are examined i n d i v i d u a l l y . F8 i s in s i g n i f i c a n t and th e re i s no c o n f lic t w h ils t F9, F10 and F11 correspond v i r t u a l l y e x a c tly w ith American s p e c u la tiv e

dummies which re p re s e n t p e rio d s o f expected d o ll a r s t re n g th . T h is i s

p a r t ic u la r l y t r u e o f F10 and F11 which correspond e x a c tly w ith S8 which was s i g n i f i c a n t and c o r r e c t ly signed in the p o u n d -d o lla r estim ates but was excluded here ( t o a vo id m u l t i c o l l i n e a r i t y ) .

Consequently an a lt e r n a t i v e in t e r p r e t a t io n o f F10 and F11 would be th a t they in d ic a t e the im portance o f American r a th e r than French

in flu e n c e in the shape o f a s ig n if ic a n t and c o r r e c t ly signed S8. T h is

i s s t ro n g ly su p p o rte d by the s i m i l a r i t y o f the a c tu a l c o e f f ic ie n t s o f

F10 and F11. Thus th e re i s a case f o r a rg u in g th a t the "Blum experim ent"

v a r ia b le s a re p ic k in g up American and not French in flu e n c e s and th e re ­ fo re th e re i s no c o n f l i c t between the r e s u lt s in the p o u n d -fra n c and

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p o u n d -d o lla r e s tim a te s .

In c o n c lu s io n , i t i s c le a r th a t the performance o f the s p e c u la tiv e dummies and in d e e d , the g e n era l performance o f the two v e rs io n s o f the f r a n c -d o lla r exchange r a t e , are h ig h ly s u p p o rtiv e o f the main hypotheses in co rp o ra te d in th e model; in p a r t ic u la r , th e re i s stro n g evidence o f

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the expected r e l a t i v e p r ic e and r e l a t i v e income e f f e c t s . However,

b e fo re d e r iv in g some g e n era l co n c lu sio n s about the p o u n d -d o lla r -fr a n c t r ia n g le th re e o u tsta n d in g is s u e s have to be d e a lt w ith : f i r s t l y , the p o s s i b i l i t y o f re p la c in g the s p e c u la tiv e dummies by a " b la n k e t" proxy f o r s p e c u la tio n based on fo rw a rd exchange market data has y e t to be e m p ir ic a lly e x p lo re d ; s e c o n d ly, s in c e many o f the v a r ia b le s (most o b v io u s ly the s p e c u la tiv e dummies) appear in more than one eq ua tio n , an e x p l i c i t exam ination o f the co n siste n cy o f t h e i r perform ance would seem a p p ro p ria t e - f o r example, i f the same v a r ia b le was a sso cia ted w ith s t e r l i n g a p p re c ia tio n a g a in s t the d o l l a r but d e p re c ia tio n a g a in st the fra n c then t h i s would r e q u ir e e x p la n a tio n ; f i n a l l y , the p o s s i b i l i t y o f p o s i t iv e s e r i a l c o r r e la t io n has to be addressed since the D u rb in -

/rpQ \

Watson s t a t i s t i c s are p e r s is t e n t ly in the in d e te rm in a te range. These is s u e s a re discussed in the next s e c t io n .

( I V )

I n the d is c u s s io n o f how to e m p ir ic a lly approxim ate the

e x is te n c e o f s p e c u la tio n ( i n ch ap ter f o u r ) a v a r ie t y o f p o s s i b i l i t i e s

were d is c u s s e d . U ltim a te ly i t was decided to t r y one v a r ia n t o f each

o f the " g e n e r ic " types o f method th a t were i d e n t i f i e d : a measure aimed a t p ic k in g up the p o t e n t ia l s p e c u la tio n induced by s p e c if ic in c id e n ts

(dummy v a r i a b l e s ) and a " b la n k e t" measure (based on forw ard market

d a t a ). The form er was p r e f e r r e d f o r a number o f reasons, most

im p o rta n tly the fa c t th a t " b la n k e t" measures may p ick up n o n -s p e c u la tiv e in flu e n c e s and, at the p r a c t ic a l l e v e l , the la c k o f s u it a b le data from which to c o n s tru c t "b la n k e t" measures; in f a c t , fo r t h is l a t t e r reason - lack o f r e a d i l y a c c e ss ib le forw ard market data - the "b la n k e t" measure

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used he re co uld o n ly be t r i e d f o r exchange r a t e s in v o lv in g the pound.

Thus a s e r ie s o f re g re s s io n s were run f o r the p o u n d -d o lla r and p o u n d -fra n c exchange ra te s in which the s p e c u la tiv e dummies were dropped and re p la c e d by an SV (s p e c u la tiv e v a r i a b l e ) which consisted

o f the average th re e month fo rw a rd exchange ra te a dju ste d by the

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three month i n t e r e s t ra te d i f f e r e n t i a l . S p e c u la tio n i s thereby

in c o rp o ra te d on the b a sis o f the assumption th a t when th e re was an

a d ju ste d fo rw a rd d isco u n t (prem ium ) on a c u rre n c y , sp e c u la to rs were

e xp e ctin g i t to d e p re c ia te (a p p re c ia te ) and c a p it a l was th e re fo re flo w in g ou t o f ( i n t o ) the c o u n try in q u e s tio n in a n t ic ip a t io n , causing

the spot ra te to weaken (s t r e n g t h e n ). In b o th the p o u n d -d o lla r and

p o u n d -fra n c e q ua tio n s the SV i s co nstru cted in such a way as to be expected to have a n e g ative s ig n .

I n the p o u n d -fra n c e q u a tio n s i t d id indeed have a neg ative sign b ut was o n ly s ig n if ic a n t a t v e ry low l e v e l s (20 p e r c e n t ). In a d d itio n the two equations' perform ances were c o n s id e ra b ly worsened in terms o f h ig h e r standard e r r o r s o f the re g re s s io n and ( s l i g h t l y )

low er R -squareds and F - s t a t i s t i c s . F u rth erm o re, the Durbin-Watson

s t a t i s t i c became v e ry low in d ic a t in g the presence o f s e r i a l c o rre la ­

t io n . In s o f a r as t h is could be taken as evidence o f om itted v a ria b le s

(which i s a p o s s ib le cause o f s e r i a l c o r r e l a t i o n ) , one o f which could be th e presence o f s p e c u la tiv e c a p ita l flo w s ina deq u a tely pro xie d by the SV, i t c o u ld be in t e r p r e t e d as su g g e stin g th a t the SV picked

up le s s o f the s p e c u la tiv e in flu e n c e than the s p e c u la tiv e dummies

and so th e l a t t e r are a b e t t e r way o f m o d e llin g s p e c u la tio n in p ra c tic e (as w e ll as in t h e o r y ) .

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The SV i n the p o u n d -d o lla r estim ates was h ig h ly s i g n i f i c a n t but i n c o r r e c t l y s ig n e d . O f f s e t t in g o f f i c i a l i n t e r v e n t io n , not

picked up by th e ID , might have caused in s ig n if ic a n c e b u t a p o s it iv e