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ABACUS, Vol. 17, No. 1, 1981
NORM ECKEL
The Income Smoothing Hypothesis Revisited
Key words: Accounting procedures; Averaging; Income measurement.
1. INTRODUCTION
The purpose of this paper is to review earlier studies of income
smoothing, and to offer an alternative conceptual framework for
detecting or identifying income smoothing behaviour of firms. There
has been a number of studies conducted in the area; however, the
conceptual framework for most of these studies tended to be similar
with differences limited to the sample of firms, the expectancy
model ussd, the time-frame studied, or the soothing objects and
smoothing variables considered. The present study proposes a
conceptually different manner of viewing income smoothing
behaviour.
The supposition that firm may intentionally smooth income was
fist suggested by Hepworth [1953] and further elaborated upon by
Gordon [1966]. The latter constructed a framework from which one
could logically deduce the impetus for the act of income smoothing.
There followed a number of empirical studies (Copeland and Licastro
[1968], Copeland and Wojdak [19691, Cushing [1969], Simpson [1969],
White [1970], Ronen and Sadan [1975], Barnea, Ronen and Sadan
[1976]) all aimed at ascertaining whether or not firms
intentionally smooth reported income.* The general findings of
these and other such studies, suggest that fkms do behave as if
they are smoothing income, although there was not complete
unanimity.
2. TYPES OF INCOME SMOOTHING The identification of income
smoothing behaviour poses no trivial task for the researcher.
Income smoothing behaviour is diagrammatically presented in Figure
1. The necessity to distinguish between the potentially different
types of smooth income streams has been recognized in previous
studies of income smoothing behaviour. Dascher and Malcolm ([1970],
pp. 253-4), Shank and Burnell ([1974], p. 136) and Horwiu ([1977],
p. 27) all made similar distinctions.
A naturally smooth income stream simply implies that the income
generating process inherently produces a smooth income stream. For
example, one would expect the income generating process of public
utilities to be such that income streams would be
I The conceptual framework employed by most researchers was
similar to that proposed by Gordon ([1966],
* See Ronen, Sadan and Snow [1977] for an excellent review of
the income smoothing literature.
NORM ECKEL is an Assistant Professor of Accounting and MIS,
Bowling Green State University, Ohio.
p. 223). Hereafter it will be termed the Gordon methodology.
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I N C O M E S M O O T H I N G H Y P O T H E S I S
FIGURE 1
Smooth Income
1, Intentionally Being
Smoothed by Management
1
Smoothing
naturally smooth. But both real and artificial smoothing are the
result of actions taken by management.
Real smoothing represents management actions undertaken to
control underlying economic events. Horwitz ([1977], p. 27) asserts
that real smoothing affects cash flows whereas artificial smoothing
does not. Dascher and Malcolm ([1970], pp. 253-4) indicate that
real smoothing represents actual transactions undertaken or not
undertaken on the basis of its smoothing effect on income. For
example, a lirm might select capital projects on the basis of the
co-variance of their expected income series. This represents the
control of actual economic events that directly affect future
income, and is thus termed real smoothing.
Artificial smoothing represents accounting manipulations
undertaken by management to smooth income. These manipulations do
not represent underlying economic events or affect cash flows, but
shift costs and/or revenues from one period to another. For
example, a firm could increase or decrease reported income simply
by changing its actuarial assumptions concerning pension
costs.)
3. PREVIOUS IDENTIFICATION OF INCOME SMOOTHING BEHAVIOUR: THE
GORDON METHODOLOGY
Copeland ([1968], p. 105) suggests three general methods for
identifying income smoothing behaviour: (1) directly ascertain from
management by interview, questionnaire, or observation; (2) contact
second parties such as CPAs; or (3) examine
For other examples of artificial smoothing and its accounting
manipulations, see Ronen ef a/. ([1977], pp. 17-19).
29
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A B A C U S
ex post data. By far the great majority of researchers selected
the last method. In fact, I know of no such studies that utilized
the other methods.
Generally speaking, those researchers examining expost data have
assumed the same conceptual framework; that is, if the variability
of normalized earnings generated by a specified expectancy model is
lessened by the inclusion of a potential smoothing variable
utilized by the firm, then the firm has smoothed income.
The problems inherent in the use of the above conceptual
framework are now examined. Firstly, these examinations require the
specification of an expectancy model for normalized income which is
indeed a difficult task. If the expectancy model does not
adequately describe the process generating the income time series,
the inferences made concerning the inclusion of a specific
smoothing variable could be a function of random error. Some
researchers used what is generally termed the naive prediction
model (El = El-,), in which the preceding periods income becomes
the predicted income for the next period. Other researchers used a
linear time trend model, exponential smoothing model, Box-Jenkins
Model or some other method of generating a normalized ir~corne.~
One common element of these expectation models is that in all of
them, El (earnings at time t) is a function of time, a constant
growth rate, or pre-specified parameters (exponential- smoothing,
Box-Jenkins, etc). Imhoff [1977] was the fmt to suggest that
normalized earnings could be a function of an independent variable
rather than the above. The independent variable selected by Imhoff
was sales, with the implicit assumption that sales revenues are not
subject to smoothing, or are subject only to a minimal e ~ t e n t
. ~
Secondly, and more importantly, the examination of one smoothing
variable at a time on the normalized income stream could produce
biased results. The smoothing effect of one potential smoothing
variable on the normalized income stream could possibly be
mitigated by the aggregate effect of several potential smoothing
variables on the normalized income stream. In other words, it may
be possible that managements selection of some variables tends to
smooth income, whereas their selection of other variables tends to
work in the opposite direction, thereby affording no conclusive
evidence for the income smoothing hypothesis.
Finally, some studies examined the effect of a potential
smoothing variable on the normalized income of one period only.
Clearly, as indicated by Copeland ([1968], p. 107) and Imhoff
([1977], p. 86), any inferences concerning income smoothing
behaviour made from a cross-sectional (one-period) study are
tenuous at best. To be sure, when making inferences concerning
income smoothing behaviour, one is implicitly alluding to a pattern
of behaviour over time, not just in a single period. Therefore,
empirical tests of income smoothing behaviour should be conducted
on time series data.
4. IMHOFFS IDENTIFICATION OF INCOME SMOOTHING Imhoff [1977]
offered a radically different framework for the identification of
income smoothing behaviour. Rue ([1977], p. 101) indicates that
Imhoffs concern that the results of previous studies of income
smoothing behaviour might have reached
See Ronen er a/. ([1977], p. 21) for a discussion of expectation
models. Imhoffs procedure will be further elaborated upon in Part 4
of this study.
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I N C O M E S M O O T H I N G H Y P O T H E S I S
inconclusive results because of the inclusion of natural
smoothers in their samples led him to construct an alternative
methodology for the identification of income smoothers.
Imhoff first regressed income and sales on time: Income = a + p
(time) and Sales = a + p (time). He then defined variability as the
size of R2 for each regression. For example, if the R2 of sales as
a function of time is greater than the R2 of income as a function
of time (R2(s = f (t) ) ) > (R2(I = f (t) ) ), then the sales
time series is defined as less variable than the income time
series. Additionally, Imhoff regressed income on sales (I = f ( s )
) to determine the extent to which income is related to sales.
To determine whether or not a specific firm was exhibiting
smoothing behaviour, Imhoff (p. 92) applied the following
criteria:
(i) . . . we define smoothing to be a smooth income stream and a
weak association between sales and income, or
(ii) a smooth income stream and a variable sales stream. He
concludes from the data analyzed that there was not a single case
of obvious smoothing. As before, with the discussion of the Gordon,
the difficulties associated with the conceptual framework will be
examined.
The first difficulty that one would encounter when attempting to
use the Imhoff methodology would be to establish how smooth is a
smooth income stream, how weak is a weak association between sales
and income, and how variable is a variable sales stream. In other
words, Imhoff did not state the cutoff points of his criteria; the
present study attempts to remedy this deficiency.
A second difficulty of the Imhoff methodology is his reliance on
the R2s of regressions 011 time as the measure of variability. For
example, consider the following information:6
dollar( $)
- 1 - - 6 Income (R2 = .lo) (R*(I=f(s))) is small
0 time (t) Imhoff would conclude from the above information that
the firm is a non-smoother because the variability of income is
greater than the variability of sales, and the relationship between
income and sales is small (per his definition that the larger the
R2 the lower the variability). Let us examine a perhaps more
realistic example of the same difficulty:
Although the reduction of income variability at the expense of
displaying slower growth is somewhat unrealistic, it is
nevertheless possible.
31
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A B A C U S
dollar ($)
(ii) Income (R2 = .60) (R2(1=f(s))) is small
> time (1)
In this example, Imhoff would conclude that the firm is a
smoother because the income stream is less variable than the sales
stream (per his notion of variability). Alternative notions of
variability could lead to opposite conclusions for both of these
examples.
5 . PROPOSED CONCEPTUAL FRAMEWORK
The proposed conceptual framework attempts to overcome the
perceived weaknesses of those used previously to detect income
smoothing behaviour.
The primary difficulty with the Gordon methodology is its
assumption that if a firms selection of a single accounting
variable tends to smooth income (given a specific expectation
model), then that firm is prima facie, an income smoother. The
primary difficulty with the Imhoff methodology is his reliance on
the R2s of income and sales regressed on time as the measure of
variability.
The proposed conceptual framework suggests that an income
smoothing firm is one that selects n number of accounting variables
such that their joint effect is to minimize the variability of its
reported income. For example, if (A) is the set of all possible
accounting variables that could be utilized by the firm, and si
represents one of many possible combinations of these variables,
then the income smoothing firm will attempt to:
n Minimize: S,CA - C. (x,~-E(X) )* where x is the annual
reported income, N-1 j=1 and j represents time in years.
Recalling Figure 1 of this study, where three types of income
smoothers were identified, it should be made explicit that the type
of income smoothing behaviour that this study is attempting to
identify, is artificial smoothing.-Because natural smoothness is
not the result of any overt actions on the part of management, and
real smoothing represents an underlying economic reality, they are
not relevant to this study. On the other hand, artificial smoothing
represents intentional management actions undertaken
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I N C O M E S M O O T H I N G H Y P O T H E S I S
to smooth the reported income timeseries and thus distort the
representation of economic reality. Moreover, the proposed
conceptual framework of this paper is used to identify only
successful income smoothing behaviour. As with the Gordon and
Imhoff methodologies, the model utilized in this study cannot
identify unsuccessful attempts by managers to smooth artifically
the reported income time-series.
It appears to me that a major problem with Imhoffs conceptual
structure is that he assumed that all three types of income
smoothness (naturally smooth, real smoothed, artificially smoothed)
must be mutually exclusive. The present study explicitly assumes
them not to be mutually exclusive. Imhoff (p. 87) states that a
firm with an extremely high degree of income variability might be
classified as an income smoother. Of course, Imhoff considers this
to be incorrect. However, this researcher considers that to be
possible. For example, a company that is in the electric utility
industry (naturally smooth) that does not practice either real or
artificial smoothing may nevertheless have an income stream that is
less variable than a company in the automobile industry that does
practice artificial smoothing.
Therefore, it is not the degree of variability in the income
time series (in any absolute sense) that the income smoothing
hypothesis is addressing, but rather whether or not the reported
income variability is a function of any overt actions undertaken on
the part of management to explicitly reduce the variability of
reported income and distort the representation of the economic
reality of the firm.
First, some premises should be stated: 1. Income is a linear
function of sales: Income = Sales - Variable Costs - Fixed
costs. 2. The ratio of variable costs in dollars to sales in
dollars remains constant over time. 3. Fixed costs may remain
constant or increase from period to period, but may not be
4. Gross sales can only be intentionally smoothed by real
smoothing; that is, gross
The four research premises represent my a priori assumptions,
and as such remain open to empirical validation. The premises are
general in nature and are assumed to be reasonable representations
of real world phenomena. It is not known how large deviations from
the premises would need to be before the veracity of the research
results could be questioned.
reduced.
sales cannot be artificially smoothed.
Given premises 1 to 4, the following conclusions may be
stated:
If
and C 2 > 0
I = s - c,s- c,
and c2,1+1 3 c2, and
and
then CVAS 1. c v ~ ?
0 < C, < 1 Cl.t+l = C1,t = c,
The proof of this relationship is contained in Appendix B.
33
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A B A C U S
where: I = income in dollars;*
S
c2 = fixed costs;
c, = variable cost ratio, ie, the ratio of variable costs to
sales; CV,, = the coefficient of variation for the change in sales
time series;
CV,, = the coefficient of variation for the change in income
time series.
Given the previous analyses, one part of the testing procedure
is to determine whether the specified variability measure of sales
is greater than the same variability measure of income. If not, it
would appear at first glance that the firm is artificially
smoothing. In addition to the first test, it was considered
necessary to add an 'industry filter'. For example, what if there
were the unlikely situation that most of the firms in a particular
industry had income time series that were less variable than their
sales time series? It would indicate an unusual process underlying
the relationship between sales and income, which would negate the
assertion of premises 1 to 4.9 Therefore, dual tests were used.
Tests for Artijcial Smoothing
= sales revenues in dollars;
and
If cv,,, > cv,, 1 " and d, > 1 u smaller than {- P I CVAIi
i CV,? I ]
then the firm is an artijcial smoother
where:
n i=l
(ii) d, = I CVAIi t CV,? I
To illustrate this procedure, a hypothetical example should
prove beneficial. Assume that industry A consists of four different
firms identified as numbers 1, 2, 3 and 4. Furthermore, assume the
following:
Firm 1: CV,, = 2.024, CV,, = 6.322 Firm2: CV,, = 4.876, CV,, =
2.667 Firm3: CV,, = 5.775, CV,, = 2.389 Firm4: CV,, = 5.367, CV,, =
2.228
If income is a linear function of sales (as postulated), it must
be assumed that [income (I) = reported income] in the absence of
income smoothing behaviour. The empirical evidence of this paper
wherein all but two of the fums' CV,, > CV,, suggests that the
research premises may be well specified.
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I N C O M E S M O O T H I N G H Y P O T H E S I S
The first part of the dual testing procedure indicates that the
CVAS > CV,, for any firm to be identified as an income smoother.
Therefore, only firm 1 appears to be a likely candidate. The second
part of the dual testing procedure then is to determine whether or
not firm 1s ICV,, + CV,, 1 is significantly less than the industry
average.]@ Given the above data, the mean ICV,, + CVAS I for the
industry is 1.74 and the standard deviation of the ratios is .99;
therefore, firm 1 would be identified as an income smoothing
firm.
6 . THE EMPIRICAL STUDY
Given the purpose of the present research to offer an
alternative conceptual framework and an alternative schema with
which to identify income smoothers, it was deemed appropriate to
test both the Gordon and the Imhoff methodologies with that of this
study.
A study by Barnea et al. [1976] was selected as the base study
with which to undertake this comparative analysis. Barnea et al.
used the Gordon methodology on a sample of 62 firms over the years
1951-1970 to examine whether these firms artificially smoothed
reported operating income by discretionary manipulation of
extraordinary items. The present empirical examination will use the
income smoothing tests of Imhoff, and the conceptual framework
proposed here on the same sample of 62 firms and same twenty year
time frame as the Barnea et al. study. The results of these three
tests of income smoothing behaviour will be evaluated relative to
each other.
Results and Conclusions Table 1 presents a summary of the
analyses for the sixty-two companies that comprised the sample.
As previously discussed, Imhoff did not fully describe his
methods of identifying income smoothing behaviour; therefore, I can
only deduce that identification. The asterisks in Table 1 depict
those firms that had a smoother income time series than sales time
series. Therefore, using Imhoffs definition, only eight firms or 13
per cent of the sample firms exhibited income smoothing
behaviour.
The methodology proposed in this paper resulted in the
identiation of only two firms or approximately 3 per cent of the
sample firms that appeared as ifthey were smoothing their income
during the twenty year period. These two firms, numbers 31 and 34,
were both in the chemical industry. Both firms had (1) CV,, >
CV,,, and (2) the (CV,, + CVAS I for each firm was more than one
standard deviation smaller than the industry average, the two
elements necessary to identify the firms as income smoothers.
Moreover, it is noteworthy that both of the firms were also
identified as income smoothers by the Imhoff methodology. The
Barnea et al. study (from which the sample firms were taken)
indicated that between 50-94 per cent of the companies were
exhibiting income smoothing behaviour, with the percentages varying
as a function of the measurement of income.
I @ Although t:ie measure (using one standard deviation less
than the industry average) was ad hoc in nature, it nonetheless
appeared to me to be reasonable, given the purpose of the industry
filter.
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A B A C U S
TABLE 1 SUMMARY TABLE OF STATISTICAL ANALYSIS
Company R:S=f(t) Rz:I=f(t) R:I=f(s) CVAS A, IcvAI+cvASl
1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 * P
10 P 11 P 12 c 13 C 14 C I 5 C 16 C 17 C 18 C 19 C 20 c 21 c 22
c 23 C 24 * C 25 * C 26 C 27 C 28 C 29 C 30 C 31 t* C 32 C 33 c 34
t* c 35 c 36 C 37 c 38 C 39 A 40 A 41 A 42 A 43 A 44 * A 45 A 46 A
47 A 48 A 49 A 50 A 51 A 52 R 53 R 54 R
.869 ,979 .845 ,944 ,979 ,913 ,970 .978 ,889 ,931 .988 ,936 ,945
,943 ,956 .893 ,808 ,883 .893 ,808 ,740 ,929 .924 ,035 ,861 ,791
,950 ,778 .667 ,496 ,935 .971 ,917 .746 ,970 ,964 .917 ,980 ,899
,795 ,846 .864 ,841 - ,967 ,869 ,849 ,926 .783 .890 ,898 ,863 ,967
,891 ,490
.238 ,556 ,710 ,420 ,479 ,658 .765 .720 ,947 ,801 ,359 ,908 ,641
,171 ,878 ,622 ,800 ,402 ,177 ,602 ,733 .852 ,164 ,044 ,863 ,734
,915 .476 ,342 ,081 ,962 ,739 -.053 ,747 .512 ,823 ,870 ,515 ,027
,145 ,307 .757 -.030 ,969 ,366 ,732 ,546 .061 SO5 .553 ,396 ,684
,559 ,339
.I34 ,593 ,902 ,517 .395 ,693 ,768 .700 ,893 ,849 ,429 ,989 ,645
,213 .886 .674 ,929 ,540 .ox ,615 ,913 .838 ,069 ,728 ,945 ,726
,914 .013 .659 ,767 ,993 ,755 -.OW .832 ,566 ,800 ,808 ,374
-.015 .062 ,215 .878
-.058 ,979 ,676 .872 ,579
-.022 ,490 ,611 ,210 ,671 ,530 ,246
.709
.973 2.107 1.036 ,804 1.287 ,914 1.016 1.003 1.140 ,830 ,937
1.712 1.529 ,874 ,979 2.497 2.281 45.902 1.428 1.757 .725 1.249
9.508 1.369 1.237 1.054 1.483 3.662 3.324 .709 ,882 1.759 12.314
1.422 ,855 1.377 1.173 .866 1.238 1.01 3 .944
1.075 ,514 2.231 2.014 .879 1.737 .905 ,862 1.131 1.332 1.151
2.635
3.660 3.505 6.482 5.305 3.088 7.554 4.545 4.924 2.024 3.293
3.087 1.067 9.216 14.874 3.190 4.800 9.193
- 12.177 -350.227
1.618 3.306 4.909 6.133 11.965 2.804 4.078 1.924
23.791 6.785 ,690 9.163 18.050 5.931 2.727 3.969 3.440 9.794
-8.714 -4.74 21.120 2.579
,726 41.354 2.699 5.926 63.238 6.137 7.706
15.003
17.610
- 10.438
-170.95
-92.962
-7.159
~
5.163 3.602 3.076 5.120 3.841 5.869 4.973 4.846 2.018 2.888
3.720 1.139 5.383 9.728 3.650 4.900 3.681 5.338 7.629 1.133 1.882
6.772 4.910 1.258 2.048 3.297 1.825 7.038 6.497 2.041 ,974
10.389 10.261 .482 1.918 4.642 2.498 8.349 10.06 3.829 20.849
2.732
159.025 1.412 18.536 1.340 6.741
6.781 8.940 92.194 11.263 6.22 6.683
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I N C O M E S M O O T H I N G H Y P O T H E S I S
TABLE 1 - continued SUMMARY TABLE OF STATISTICAL ANALYSIS
ampany R2:S=f(t) R:I=f(t) R2:I=f(s) CVAS CV,, lCVAl+CVA,
55 * R .747 .835 ,630 1.582 4.480 2.832 56 R .852 ,793 ,863
1.374 4.792 3.487 57 R ,874 - ,000 -.051 1.902 -8.259 4.343 58 * R
,866 ,887 .953 1.252 2.209 1.765 59 R ,630 ,190 ,400 8.356 22.561
2.700 60 R .876 ,640 ,620 1.464 32.064 2 1.902 61 R ,928 ,850 ,914
,720 I .952 2.71 1 62 R .850 .099 .27Q 14.460 -46.585 3.22
Nores: P = pulp and paper industry, C = chemical industry; A =
air transport industry, R = rubber industry;
Rz:S = f(t) = the adjusted Rz of gross sales regressed on time;
R2:I = f(t) = the adjusted R2 of net income regressed on time; R2:I
= f(s) = the adjusted R2 of net income regressed on gross
sales;
CV,, = the coefficient of variation of the change in gross
sales; CV,, = the coefficient of variation of the change in net
income;
* = income smoothing behavior indicated by the lmhoff
methodology; t = income smoothing behavior indicated by the
proposed methodology; of this paper.
The extreme difference in findings between the Gordon
methodology employed by Barnea et al. and the methodology used here
are difficult to reconcile. Both methodologies are subject to
potential difficulties that could result in questions concerning
the veracity of their findings. The primary weaknesses of the
Gordon methodology are the necessity of normalizing the income
stream vis-a-vis some specified expectation model, and the
examination of the income smoothing effect of one accounting
variable at a time. The primary weakness of the methodology of this
paper rests with the qualitative effects of the research premises.
No account is taken of the quantitative effects of the premises.
The methodology employed here does not enable us to identify firms
which may have reduced the variance of its income series, but not
to the extent that it is less than the variance of sales. That is,
while it is shown that CV,, > CVAS no account is taken of the
magnitude of this difference. The methodology employed here is
unable to identify firms for which CV,, was significantly greater
than
CVAS and which were still smoothing, but not to the extent that
CV,, > CV,,. The possible distortion of findings that may result
from the use of these two different income smoothing identification
methods is at best, difficult to assess.
The empirical results reported in this paper suggest that sixty
(97 per cent) of the sample firms were not successfully
artificially smoothing their income time series. These results may
be interpreted in a couple of ways: first, that the management of
the sample firms were not overtly attempting to smooth their
respective income time series; or second, they were unable to
smooth their respective income time series. Some authors (Ball and
Watts [1972), Gonedes [1972]) offer the proposition that if the
income generating processes are of a certain type(s), then attempts
at smoothing the income time series will prove fruitless and may as
well not be undertaken.
Unlike the bulk of previous empirical findings indicating the
presence of income smoothing behaviour, the findings of the present
study suggest that firms are unable to
37
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A B A C U S
reduce the variability of their income time series below the
variability of their sales time series. For the income smoothing
hypothesis this may indicate that the jury is still out.
APPENDIX A
ARTIFICIAL SMOOTHING BEHAVIOUR
The following objectives represent the rationale for using the
coefficient of variation of the chunge in income and sales as
opposed to the ordinary coefficient of variation.
1. If income is a linear function of sales, then the variability
measure of sales should equal the variability measure of
income.
2. Companies in the same industry experiencing the same
macro-economic affects should have variability measures that are
equal.
3. Number 2 should be true regardless of the absolute sales
dollar size, or the form of the linear relationship.
For Example: Linear Relationship: I = S - .7S - 70
Macro-economic Firm 1 effect Sales
200 +20% 240 -15% 204 -10% 183.60 +30% 238.68 +20% 286.42
TI = 255.42 a,, = 31.52
CVs, = .I65
AFirm 1 Sales +40 -36 -20.4 +55.08 +47.74
AT, = 17.28 uAS, = 42.22
CVAS, = 2.44
Linear Relationship: I = S - .2S - 150
Firm 2 Sales 400 480 408 367.20 471.36 572.83
F2 = 450.89 uS2 = 74.63
CV,= .I65
AFirm 2 Sales +80 -72 -40.8
+110.16 +95.47
A q = 34.57 uAS, = 84.45
CVAS, = 2.44
-
Firm 1 Income -10
2 -8.80
-14.92 1.60
15.93 - I , = 2.365 uIt = 11.19
cv = -4.73 I 1 AFirm I Income
+I2 - 10.80 -6.12
+16.52 +14.33
A 6 = 5.19 ITAI, = 12.67
CVAI, = 2.44
-
Firm 2 Income
50 74 52.40 40.16 73.21
101.85 = 65.27
u , ~ = 22.39 CV,,= ,343
A Firm 2 Income
+24
+33.05 +28.64
-21.60 -12.24
A& = 10.37 uA12 = 25.33
C V A I , = 2.44
A Firm 1 Firm 1 Firm I A Firm 1 Sales Income Sales Income 200 10
240 42 +40 +32 204 13.20 - 36 -28.8 183.6 -3.12 -20.4 -16.32 238.6
40.88 +55.08 +44.00 286.42 79.14 47.74 +38.26
= 225.42 7 = 30.35 As; = 17.28 A q = 13.83 US, = 31.32 uI, =
29.85 UAS, = 42.22 aAI, = 33.78
CVs, = .I65 CV, = .98 CVASl = 2.44 CV,,, = 2.44 1
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I N C O M E S M O O T H I N G H Y P O T H E S I S
By using CVAX = - Ax
one is able to meet all three of the objectives slated
earlier.
APPENDIX B Define: (a) DS, = S,,, - S,;
(1) 1, = s, - C,,?, - c,,, 0) c,,t+I 2 CZ,, O
(b) DC2.t = c2,1+1 -c2,,; (c) DI, = I,,, - 1,; (dl De, = e,+, -
el;
If
where:
(ii) Cl,,+l = C,,, = C, with0 < C, < 1 (iii) C,,, = a +
kS, + e, with
Cov(DS,,De,) = 0 and E(eJ = 0 for all t
(iv) 1 - C, - k > 0 then CVAs SCV,, with CVAI = CV,, when el
= 0
Case I: (2) C,,, = a + kS,; i.e., e, ~0
It follows from (1) and definitions a, b, c, d that;
(3) DI, = (1-C,) DS, - DC,,, (by subtraction)
(4) DI, = (l-Cl-k) DS, from (2) & (3)
( 5 ) E(D1,) = (I-C,-k) E(DS,) from (4)
(6) V(D1,) = (1-C,-k)2V(DSJ from (4)
then from ( 5 ) & (6);
since 1-C,-k > 0
:. CVAS = cv,, Case 11: (7) C,,, = a + kS, + el
(8) DC,,, = kDS, + De, from (7)
(9) DI, = (I-C,)DS, - LDS, - De, from (3) & (8)
(10) DI, = (1-Cl-k) DS, - DE, from (9)
39
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A B A C U S
from (10) it follows that:
(11) E(D1,) = (l-C,-k)E(DS,)
(12) V(D1,) = (I-C,-k)*V(DS,)+V(De,)
then from (11) & (12);
since 1-C,-k > 0 :. cv,, > CV,,
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