Both the DMB and MSA studies of the overcrowding problem in Michigan county jails surveyed sheriffs on what it cost them to operate their jails. Based on these data, both studies calculated the per-inmate daily costs of operating the state's county jails.
The DMB's analysis of county jails over the 1978 — 1982 period reports a 1981 per-inmate daily operating cost of 552.46 in the Detroit-Southeastem area of the state. For the Upper Peninsula-Northern Lower Peninsula area of the state, daily per-inmate costs were calculated to be $34.26. In the rest of the state (essentially the out-Detroit, Southern Lower Peninsula area) daily per-inmate cost was $26.37. The state-wide average daily cost – clearly skewed by the higher costs found in the Wayne County-Southeastern portion of the state – was $38 or $14,494 per-inmate-per-year.  But, as the DMB report makes dear, these costs are based on estimates provided by the sheriffs surveyed. As the Department of Justice study noted above makes dear, there is a general tendency throughout the nation for true costs to be underestimated – not because respondents willfully underestimate, but because many costs are charged to the budgets of other government agencies which provide services to county jails. Nevertheless, even though charged elsewhere, these are still costs in the only sense which matters to the community: they represent absorption of present and future scarce economic resources which have the potential of producing equal or greater value to all citizens. Failure to take direct and accurate account of these cots when attention is focused on jails does not eliminate these costs, it merely disguisesthem and causes decisions to be, made with less information than the public is entitled to have in a democratic society.
The MSA studies also provide estimates of daily inmate costs from data submitted by 71 of the state's 77 county jail operators. About one-half of those reporting to MSA gave a daily cost greater than or equal to $25 per inmate with the highest being $93. Based on these reported data, the state-wide average daily operating cost per-inmate in a Michigan county jail – as of March, 1984 – was $28, not $38 as reported to DMB by the sheriffs. According to MSA, if the $28.00 figure can be considered to be accurate, the annual 1984 cost of housing an inmate in a Michigan county jail was approximately $10,220-per year . 
The MSA was careful to indicate that its survey estimates of daily costs per-inmate should be taken with "a grain of salt." Self-reporting, MSA noted, is not the best measure ofobtaining precise data and cost estimates are only accurate to the extent that respondents used the same basis for calculation. "Only to the extent that costs such as staffing, food services, maintenance ofthe physical plant, and other services are taken into account equally by all respondents, can real daily costs be reflected. We are not sure that all respondents calculated costs in the same manner. Therefore, our cost figures should be taken as qualitative and reflective rather than precisely quantitative"(emphasis added). 
DMB's figures suggest annual per-inmate operating costs of $14,494 and average per-day inmate cost of $38, based on survey results generated in 1981. MSA's figures suggest annual per-inmate operating cots of $10,220 and average per-day inmate cost of $28, based on survey data generated in 1984. How much change had occurred in Michigan's county jails in three years to suggest that per-inmate daily costs could have faller by over 26 percent?
If wages, fringe benefits, food, supplies, and general upkeep and maintenance costs had remained unchanged between the time of DMB's 1981 Cost Survey and MSA's 1984 cost survey, the only thing which could explain the substantial difference in daily inmate operating costs reported by the state's sheriffs would have teen a dramatic increase in average daily population in the state's county jails. According to the DMB survey, the 1981 average daily county jail population was 6,239.  According to the MSA, the average daily population in the state's county jails as of March, 1984, was 6095.  Average daily population counts are not difficult to obtain: all that is involved is a simple head count. Given that Michigan's sheriffs have been on record in expressing their concern about overcrowding and the need for funds to) expand jail facilities, A is not likely that daily population figures would have been underestimated. In truth, any mistake in population estimates would probably have erred in the direction of overcounting.
Given virtually unchanged population figures between 1981 and 1984 as reported by sheriffs to the DMB and MSA, the only other explanation for MSA's reported lower daily per-inmate operating costs compared to DMB's per-inmate daily operating costs would have to have been falling prices for the economic resources (labor, maintenance, supplies, etc.) sheriffs use to operate their jails between 1981 and 1984. Given that the national Consumer Price Index reveals prices some 14.2% higher in 1984 than they were in 1981, one would be pressed to assume that the prices sheriffs had been compelled to pay for the economic resources needed to operate a jail had fallen by almost 26 percent while prices in general were rising in all other areas of national economic activity.
Why the difference in the DMB and MSA figures? Did sheriffs over estimate their costs in their 1981 report to the DMB or did they underestimate their operating costs in their response to the 1984 MSA survey? On the assumption that Michigan's sheriffs did the best they could to report their operating costs to both surveys, there remains only one other explanation as was nationally true in the Department of Justice survey noted above, so it is also true in the survey of Michigan county jails, no one – including sheriffs – really knows what it actually costs to operate a jail.
Michigan sheriffs, like sheriffs in other states, may be quick to counter that they know what it costs to operate their jails because they're the ones who "count out the money" every day. However the public has the right to ask if there are any services rendered to inmates or to jail employees from any other sources of government – including county health departments; county payroll and pension management offices; county public defenders; county schools; county libraries; county roads and grounds crews; or any other units of government (state or federal) whose contribution to tie continual existence of a jail – including its inmates and employees – are not directly charged dollar-for-dollar to the county sheriff's department generally, and the county jail specifically. If there are – and such is the case virtually everywhere in the nation – then the sheriff is not actually giving a true account of what his office extracts from citizens for the management of his county jail. I want to emphasize that such oversight is purposeful and sinister. It is the result of the highly segmented nature of government accounting and cost allocation procedures. In truth the sheriff may not know the value of all resources tied-up in fulfilling his jail management responsibilities.