- Email: [email protected]
State Population as a Predictor of Radiation Therapy Staffing Levels
State Population as a Predictor of Radiation Therapy Staffing Levels John Culbertson, MA, MEd, Kira Carbonneau, MEd, Myke Kudlas, MEd
Purpose: Considering the cyclical nature of shortages and oversupplies of staffing levels in the labor force, an accurate prediction of future demand for personnel is of great importance. Historically, the profession of radiation therapy has been plagued with these cycles. This study establishes state population as a strong predictor of radiation therapy staffing levels. Methods: A linear regression analysis was performed to determine the association between state population and radiation therapy staffing levels from 2002 to 2010. Results: State population is a significant and substantial predictor variable for the number of actively employed and registered radiation therapists, with 89.5% to 91.4% of the variance accounted for from 2002 to 2010. Conclusions: Additional research in estimating future demand in radiation therapy is possible. By monitoring change in state population, health care professionals can proactively address cycles of shortages and oversupplies in staffing levels. Key Words: Radiation therapy, staffing levels, supply, demand, census, population J Am Coll Radiol 2012;9:358-362. Copyright © 2012 American College of Radiology
INTRODUCTION
Considering the cyclical nature of shortages and oversupplies of staffing levels in the labor force, an accurate prediction of future demand for personnel is of great importance. Historically, the profession of radiation therapy has been plagued with these cycles [1]. This study establishes state population as a strong predictor of radiation therapy staffing levels. The prediction of future need for health care staffing is beneficial for both health care educators and management. With this association, additional research in calculating future demand in radiation therapy at the state level is possible. By monitoring change in state population, health care professionals can proactively address cycles of shortages and oversupplies in staffing levels.
Registry of Radiologic Technologists. Criteria for selection included all registrants who identified themselves as actively employed, either primarily or secondarily, in radiation therapy. A linear regression analysis was performed to determine the association between state population and radiation therapy from 2002 to 2010. RESULTS
As seen in Table 1, state population is a significant and substantial predictor variable for radiation therapy, with 89.3% to 91.4% of the variance accounted for from 2002 to 2010. Figures 1 and 2 illustrate the relative consistency in the expansion of the number of therapists as state populations increased over the 8-year period (Table 2).
METHODS
Total US population census data taken from the US Census Bureau were gathered for all 50 states and the District of Columbia from 2002 to 2010 [2]. For the purpose of this study, state population is considered the predictor variable. Radiation therapy state population census data from 2002 to 2010 was made available by the American
American Society of Radiologic Technologists, Albuquerque, New Mexico. Corresponding author and reprints: John Culbertson, MA, MEd, American Society of Radiologic Technologists, 13000 Central Avenue SE, Albuquerque, NM 87123; e-mail: [email protected].
358
An Explanation of Outlier States (Pennsylvania, Florida, and California) With a Further Dimension of the Model
Two states (Pennsylvania and Florida) consistently appear well above the regression line, while California appears below it (see Figures 1 and 2). In 2006, the Health Outcomes Research Group conducted a comprehensive study of the total number of radiation therapy facilities across the United States [3]. In that study, the investigators also gathered information on the total number of patients who were treated for cancer in 2004. Cross-tabulations of these data were broken down by state. © 2012 American College of Radiology 0091-2182/12/$36.00 ● DOI 10.1016/j.jacr.2011.12.011
Culbertson, Carbonneau, Kudlas/State Population and RT Staffing Levels 359
Table 1. Regression models for state population (predictor variable) and number of radiation therapists (dependent variable) Unstandardized Coefficient () Year r2 t p 2002 2003 2004 2005 2006 2007 2008 2009 2010
0.895 0.893 0.899 0.908 0.908 0.918 0.906 0.906 0.914
3.31 3.51 3.63 3.75 3.88 4.03 4.16 4.24 4.35
⫻ ⫻ ⫻ ⫻ ⫻ ⫻ ⫻ ⫻ ⫻
10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5
20.466 20.267 20.851 22.155 22.032 21.992 21.775 21.725 22.813
⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001
Fig 1. Scatterplot of active registered radiation therapists by state population, 2002.
Fig 2. Scatterplot of active registered radiation therapists by state population, 2010.
A linear regression analysis of those 2004 data (see Figure 3) reveals that the staffing demand in Pennsylvania and Florida (the outlier states, with the exception of California) is indeed higher, as reflected by the association between actively employed therapists and the number of patients being treated for cancer ( ⫽ 0.009, p ⬍ .001), with 97.5% of the variance accounted for by these patients (Table 2). Consequently, the supply, in the form of actively employed therapists, is higher in Pennsylvania and Florida. Although the supply and demand differential for California is not completely accounted for by factoring in patients treated for cancer, the gap between California and the regression line does narrow. Further research would be required to determine why the
supply of therapists in California is lower than the expected value, as reflected by the regression model. Possible Additional Predictor Variables Educational Programs. Multicollinearity, a common problem seen in regression analysis, may exist with other predictor variables accounting for variance in radiation therapy. For instance, the number of educational programs [4] in a given state (M, 2.0 ⫾ 2.1; n ⫽ 51) correlates strongly with radiation therapy (M, 318.2 ⫾ 318.1; n ⫽ 51) (r[51] ⫽ 0.893, p ⬍ .001; see Table 2 for educational programs and radiation therapy data). However, as a single predictor, education programs (r2 ⫽ 0.797) are not as strong as state population (r2 ⫽ 0.914).
360 Journal of the American College of Radiology/ Vol. 9 No. 5 May 2012
Table 2. State population, registered radiation therapists actively employed, patients treated for cancer, facilities, wage and salary, and educational programs SP T PTC F WS EP State 2002 2010 2002 2004 2010 2011 2004 2004 2010 2011 Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware District of Columbia Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming
4,472,420 642,691 5,452,108 2,704,732 34,876,194 4,504,265 3,448,382 804,131 579,585 16,680,309 8,585,535 1,228,069 1,342,149 12,558,229 6,149,007 2,929,264 2,712,598 4,091,330 4,466,068 1,293,938 5,439,913 6,440,978 10,038,767 5,017,458 2,858,643 5,680,852 909,868 1,725,083 2,166,214 1,271,163 8,544,115 1,850,035 19,161,873 8,316,617 633,617 11,420,981 3,484,754 3,517,111 12,326,302 1,066,034 4,103,934 762,107 5,803,306 21,710,788 2,334,473 614,950 7,283,541 6,056,187 1,799,411 5,446,766 497,069
4,779,736 710,231 6,392,017 2,915,918 37,253,956 5,029,196 3,574,097 601,723 897,934 18,801,310 9,687,653 1,360,301 1,567,582 12,830,632 6,483,802 3,046,355 2,853,118 4,339,367 4,533,372 1,328,361 5,773,552 6,547,629 9,883,640 5,303,925 2,967,297 5,988,927 989,415 1,826,341 2,700,551 1,316,470 8,791,894 2,059,179 19,378,102 9,535,483 672,591 11,536,504 3,751,351 3,831,074 12,702,379 1,052,567 4,625,364 814,180 6,346,105 25,145,561 2,763,885 625,741 8,001,024 6,724,540 1,852,994 5,686,986 563,626
180 13 164 102 893 142 162 36 18 835 307 44 47 518 308 128 121 184 182 56 227 281 430 201 109 208 39 75 56 50 366 48 722 358 36 509 130 134 651 41 130 37 270 719 58 33 282 271 79 252 22
213 14 200 123 1014 170 166 41 17 953 361 50 60 551 352 137 129 192 207 64 238 292 492 221 142 223 43 92 89 50 427 55 779 402 39 569 142 156 722 45 158 44 286 814 78 39 324 296 90 296 24
242 21 276 146 1336 215 201 46 15 1164 459 54 72 681 446 163 146 227 223 73 303 392 584 281 159 285 48 123 109 77 525 69 934 539 39 677 226 187 887 46 209 54 348 1037 111 50 421 388 115 377 25
242 24 289 154 1,343 210 211 47 15 1,203 466 55 77 717 463 160 151 232 235 74 303 405 587 290 162 295 50 125 108 82 550 70 990 557 39 679 228 185 902 48 215 56 368 1,044 115 48 437 404 108 379 29
24,270 1,890 23,560 14,800 134,300 15,510 17,010 4,390 2,860 97,290 35,430 5,070 5,460 60,280 32,160 15,940 12,940 22,720 23,540 7,520 25,310 33,050 48,220 22,720 15,120 30,290 5,000 8,280 10,990 6,290 43,830 7,550 88,190 40,240 3,250 59,410 18,540 17,280 72,590 5,950 21,500 4,000 30,850 84,530 6,360 3,150 31,190 27,380 11,430 26,160 2,430
42 3 49 22 197 28 24 8 6 183 62 10 12 107 76 22 25 39 39 7 40 34 63 31 24 48 8 18 20 7 56 16 155 64 11 97 28 23 118 5 23 8 52 157 11 4 48 42 19 50 6
$66,433 $77,480 $89,261 $77,049 $103,910 $87,226 $91,185 $103,785 $77,847 $72,405 $69,757 $83,519 $69,847 $84,032 $74,826 $62,707 $64,238 $76,884 $67,783 $72,717 $77,223 $86,197 $67,311 $70,349 $69,266 $69,191 $75,494 $69,140 $82,163 $81,117 $93,348 $82,636 $89,738 $72,299 $63,353 $66,894 $69,781 $89,923 $82,419 $90,184 $73,202 $67,277 $62,600 $81,706 $77,508 $70,394 $77,620 $84,535 $56,280 $74,751 $84,124
2 — 1 2 6 1 2 1 — 8 5 — — 4 4 1 1 1 1 1 1 4 5 3 — 2 — 1 1 1 3 — 7 6 — 3 1 1 4 — — 1 3 6 1 1 2 1 1 1 —
Note: ED ⫽ educational programs; F ⫽ facilities; PTC ⫽ patients treated for cancer; SP ⫽ state populations; T ⫽ radiation therapy; WS ⫽ wage and salary.
Furthermore, there are only 101 radiation therapy programs recognized by the American Registry of Radiologic Technologists in the United States [4], with 11 states not having any programs (Alaska, the District of
Columbia, Hawaii, Idaho, Mississippi, Montana, North Dakota, New Mexico, Rhode Island, South Carolina, and Wyoming). Regardless of this relatively limited number of programs, states that do not have educa-
Culbertson, Carbonneau, Kudlas/State Population and RT Staffing Levels 361 Fig 3. Scatterplot of active registered radiation therapists by persons treated for cancer, 2004.
tional programs still have state population/radiation therapy ratios similar to those states that do have educational programs. For example, comparing the state population/radiation therapy ratio of a mostly rural state (Wyoming) with zero education programs with that of a large urban state (New York) with a high number of education programs (n ⫽ 7) reveals similar ratios (New York, 20,747:1; Wyoming, 22,545:1). In addition, the mean state population/radiation therapy ratio across all states is 20,161:1 (SD, 4,931). This indicates that states that do not have EPs are successful in recruiting radiation therapists from other states to meet their demand. This in turn illustrates that state population is the more parsimonious fit for T [5]. Urban and Academic Centers. An assumption could be
made that urban areas with academic centers and facilities with higher levels of technology would attract a large number of staff members. As with the state population/radiation therapy ratio determined above, we can compute the ratio of therapists per facility and make comparisons among differing states [3]. As seen in Table 2, California has the highest number of facilities (n ⫽ 197) and Alaska the lowest (n ⫽ 3), but the ratios of therapists to facilities are very similar (California, 5.1:1; Alaska, 4.7:1), with the mean number of therapists per facility across all states being 5.8 ⫾ 1.4. This indicates that the number of facilities in a state does not necessarily drive staffing numbers but rather the demand in that state, which can be predicted by state population. Conventionally, variability in salary is often thought of as an indicator of the relative degree to which demand is being met by equilibrium, oversupply, or shortage in supply. Salary data collected from radiation therapists in the American Society of Radiologic Technologists 2010 Wage and Salary Survey [6] (M, $77,076 ⫾ $10,268; n ⫽ 51) does not significantly correlate with radiation therapy (M, 310.4 ⫾ 310.9; n ⫽ 41) by state (r[51] ⫽ 0.240, p ⫽ .089; see Table 2 for wage and salary and radiation therapy data). This illustrates that salary is very complex, with many factors affecting its variance, such as cost-of-living differences within regions (eg, rural, urban, suburban), employee experience, education
level, as well as other variables, and does not contribute as a predictor of radiation therapy with state population in a multiple regression model ( ⫽ ⫺0.002, p ⫽ .085). Limitations
Significant increases in demand over a short time span at the state level could dramatically alter projections of needed supply. Likewise, unexpected shifts in state population would have a similar effect. Controlling for such changes in computing projected demand is recommended, if such patterns are evident. Advancements in technology could also create efficiencies in which the number of staff members needed for patient throughput and workload becomes lower. A possible additional limitation is that any changes in year-to-year facility reimbursement that occur across states could potentially affect staffing patterns. Further research would be required to determine if this is a significant factor that accounts for variability in the model. The association between state population and the number of actively employed radiation therapists does not determine if facilities are appropriately staffed in relation to actual patient throughput and workload. It merely illustrates the relative consistency and equilibrium of staffing levels that occur with state population as a predictor variable. Further research could be conducted to determine if radiation therapists and managers believe their facilities to be appropriately staffed, given actual levels of patient throughput and workload.
Salary.
CONCLUSIONS
This study establishes the association of state population as a significantly strong predictor of radiation therapy staffing levels. Factoring in the number of patients treated in a given state strengthens the model further accounting for an even higher percentage of the variability in radiation therapy staffing levels. Although multicollinearity exists with the number of EPs found in a given state, as a single factor, state population is the more parsimonious fit. Other variables such as salary do not contribute as significant predictors of radiation therapy staffing levels in a multiple regression model.
362 Journal of the American College of Radiology/ Vol. 9 No. 5 May 2012
With state population as a predictor variable, health care professionals can address cycles of shortages and oversupplies of radiation therapy staffing supply by making comparative analyses of changes across these populations. By monitoring these changes, it is possible to estimate future demand for radiation therapy staff members at the state and aggregated national levels.
2. US Census Bureau. National and state population estimates, 2000-2010. Available at: http://www.census.gov/popest/intercensal/state/state2010. html. Accessed November 18, 2011. 3. Ballas LK, Elkin EB, Schrag D, Minsky BD, Bach PB. Radiation therapy facilities in the United States. Int J Radiat Oncol Biol Phys 2006;66:1204-11. 4. American Registry of Radiologic Technologists. ARRT-recognized educational programs. Available at: https://www.arrt.org/Education/EducationalPrograms. Accessed November 18, 2011.
REFERENCES
5. Bentler PM, Mooijaart A. Choice of structural model via parsimony: a rationale based on precision. Psychol Bull 1989;106:315-7.
1. American Society of Radiologic Technologists. Radiation Therapy Staffing Survey. Available at: https://www.asrt.org/content/RTs/Research/research. aspx. Accessed November 18, 2011.
6. American Society of Radiologic Technologists. 2011 Wage and Salary Survey. Available at: https://www.asrt.org/content/RTs/Research/research. aspx. Accessed November 18, 2011.
Purpose: Considering the cyclical nature of shortages and oversupplies of staffing levels in the labor force, an accurate prediction of future demand for personnel is of great importance. Historically, the profession of radiation therapy has been plagued with these cycles. This study establishes state population as a strong predictor of radiation therapy staffing levels. Methods: A linear regression analysis was performed to determine the association between state population and radiation therapy staffing levels from 2002 to 2010. Results: State population is a significant and substantial predictor variable for the number of actively employed and registered radiation therapists, with 89.5% to 91.4% of the variance accounted for from 2002 to 2010. Conclusions: Additional research in estimating future demand in radiation therapy is possible. By monitoring change in state population, health care professionals can proactively address cycles of shortages and oversupplies in staffing levels. Key Words: Radiation therapy, staffing levels, supply, demand, census, population J Am Coll Radiol 2012;9:358-362. Copyright © 2012 American College of Radiology
INTRODUCTION
Considering the cyclical nature of shortages and oversupplies of staffing levels in the labor force, an accurate prediction of future demand for personnel is of great importance. Historically, the profession of radiation therapy has been plagued with these cycles [1]. This study establishes state population as a strong predictor of radiation therapy staffing levels. The prediction of future need for health care staffing is beneficial for both health care educators and management. With this association, additional research in calculating future demand in radiation therapy at the state level is possible. By monitoring change in state population, health care professionals can proactively address cycles of shortages and oversupplies in staffing levels.
Registry of Radiologic Technologists. Criteria for selection included all registrants who identified themselves as actively employed, either primarily or secondarily, in radiation therapy. A linear regression analysis was performed to determine the association between state population and radiation therapy from 2002 to 2010. RESULTS
As seen in Table 1, state population is a significant and substantial predictor variable for radiation therapy, with 89.3% to 91.4% of the variance accounted for from 2002 to 2010. Figures 1 and 2 illustrate the relative consistency in the expansion of the number of therapists as state populations increased over the 8-year period (Table 2).
METHODS
Total US population census data taken from the US Census Bureau were gathered for all 50 states and the District of Columbia from 2002 to 2010 [2]. For the purpose of this study, state population is considered the predictor variable. Radiation therapy state population census data from 2002 to 2010 was made available by the American
American Society of Radiologic Technologists, Albuquerque, New Mexico. Corresponding author and reprints: John Culbertson, MA, MEd, American Society of Radiologic Technologists, 13000 Central Avenue SE, Albuquerque, NM 87123; e-mail: [email protected].
358
An Explanation of Outlier States (Pennsylvania, Florida, and California) With a Further Dimension of the Model
Two states (Pennsylvania and Florida) consistently appear well above the regression line, while California appears below it (see Figures 1 and 2). In 2006, the Health Outcomes Research Group conducted a comprehensive study of the total number of radiation therapy facilities across the United States [3]. In that study, the investigators also gathered information on the total number of patients who were treated for cancer in 2004. Cross-tabulations of these data were broken down by state. © 2012 American College of Radiology 0091-2182/12/$36.00 ● DOI 10.1016/j.jacr.2011.12.011
Culbertson, Carbonneau, Kudlas/State Population and RT Staffing Levels 359
Table 1. Regression models for state population (predictor variable) and number of radiation therapists (dependent variable) Unstandardized Coefficient () Year r2 t p 2002 2003 2004 2005 2006 2007 2008 2009 2010
0.895 0.893 0.899 0.908 0.908 0.918 0.906 0.906 0.914
3.31 3.51 3.63 3.75 3.88 4.03 4.16 4.24 4.35
⫻ ⫻ ⫻ ⫻ ⫻ ⫻ ⫻ ⫻ ⫻
10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5 10⫺5
20.466 20.267 20.851 22.155 22.032 21.992 21.775 21.725 22.813
⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001 ⬍.001
Fig 1. Scatterplot of active registered radiation therapists by state population, 2002.
Fig 2. Scatterplot of active registered radiation therapists by state population, 2010.
A linear regression analysis of those 2004 data (see Figure 3) reveals that the staffing demand in Pennsylvania and Florida (the outlier states, with the exception of California) is indeed higher, as reflected by the association between actively employed therapists and the number of patients being treated for cancer ( ⫽ 0.009, p ⬍ .001), with 97.5% of the variance accounted for by these patients (Table 2). Consequently, the supply, in the form of actively employed therapists, is higher in Pennsylvania and Florida. Although the supply and demand differential for California is not completely accounted for by factoring in patients treated for cancer, the gap between California and the regression line does narrow. Further research would be required to determine why the
supply of therapists in California is lower than the expected value, as reflected by the regression model. Possible Additional Predictor Variables Educational Programs. Multicollinearity, a common problem seen in regression analysis, may exist with other predictor variables accounting for variance in radiation therapy. For instance, the number of educational programs [4] in a given state (M, 2.0 ⫾ 2.1; n ⫽ 51) correlates strongly with radiation therapy (M, 318.2 ⫾ 318.1; n ⫽ 51) (r[51] ⫽ 0.893, p ⬍ .001; see Table 2 for educational programs and radiation therapy data). However, as a single predictor, education programs (r2 ⫽ 0.797) are not as strong as state population (r2 ⫽ 0.914).
360 Journal of the American College of Radiology/ Vol. 9 No. 5 May 2012
Table 2. State population, registered radiation therapists actively employed, patients treated for cancer, facilities, wage and salary, and educational programs SP T PTC F WS EP State 2002 2010 2002 2004 2010 2011 2004 2004 2010 2011 Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware District of Columbia Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming
4,472,420 642,691 5,452,108 2,704,732 34,876,194 4,504,265 3,448,382 804,131 579,585 16,680,309 8,585,535 1,228,069 1,342,149 12,558,229 6,149,007 2,929,264 2,712,598 4,091,330 4,466,068 1,293,938 5,439,913 6,440,978 10,038,767 5,017,458 2,858,643 5,680,852 909,868 1,725,083 2,166,214 1,271,163 8,544,115 1,850,035 19,161,873 8,316,617 633,617 11,420,981 3,484,754 3,517,111 12,326,302 1,066,034 4,103,934 762,107 5,803,306 21,710,788 2,334,473 614,950 7,283,541 6,056,187 1,799,411 5,446,766 497,069
4,779,736 710,231 6,392,017 2,915,918 37,253,956 5,029,196 3,574,097 601,723 897,934 18,801,310 9,687,653 1,360,301 1,567,582 12,830,632 6,483,802 3,046,355 2,853,118 4,339,367 4,533,372 1,328,361 5,773,552 6,547,629 9,883,640 5,303,925 2,967,297 5,988,927 989,415 1,826,341 2,700,551 1,316,470 8,791,894 2,059,179 19,378,102 9,535,483 672,591 11,536,504 3,751,351 3,831,074 12,702,379 1,052,567 4,625,364 814,180 6,346,105 25,145,561 2,763,885 625,741 8,001,024 6,724,540 1,852,994 5,686,986 563,626
180 13 164 102 893 142 162 36 18 835 307 44 47 518 308 128 121 184 182 56 227 281 430 201 109 208 39 75 56 50 366 48 722 358 36 509 130 134 651 41 130 37 270 719 58 33 282 271 79 252 22
213 14 200 123 1014 170 166 41 17 953 361 50 60 551 352 137 129 192 207 64 238 292 492 221 142 223 43 92 89 50 427 55 779 402 39 569 142 156 722 45 158 44 286 814 78 39 324 296 90 296 24
242 21 276 146 1336 215 201 46 15 1164 459 54 72 681 446 163 146 227 223 73 303 392 584 281 159 285 48 123 109 77 525 69 934 539 39 677 226 187 887 46 209 54 348 1037 111 50 421 388 115 377 25
242 24 289 154 1,343 210 211 47 15 1,203 466 55 77 717 463 160 151 232 235 74 303 405 587 290 162 295 50 125 108 82 550 70 990 557 39 679 228 185 902 48 215 56 368 1,044 115 48 437 404 108 379 29
24,270 1,890 23,560 14,800 134,300 15,510 17,010 4,390 2,860 97,290 35,430 5,070 5,460 60,280 32,160 15,940 12,940 22,720 23,540 7,520 25,310 33,050 48,220 22,720 15,120 30,290 5,000 8,280 10,990 6,290 43,830 7,550 88,190 40,240 3,250 59,410 18,540 17,280 72,590 5,950 21,500 4,000 30,850 84,530 6,360 3,150 31,190 27,380 11,430 26,160 2,430
42 3 49 22 197 28 24 8 6 183 62 10 12 107 76 22 25 39 39 7 40 34 63 31 24 48 8 18 20 7 56 16 155 64 11 97 28 23 118 5 23 8 52 157 11 4 48 42 19 50 6
$66,433 $77,480 $89,261 $77,049 $103,910 $87,226 $91,185 $103,785 $77,847 $72,405 $69,757 $83,519 $69,847 $84,032 $74,826 $62,707 $64,238 $76,884 $67,783 $72,717 $77,223 $86,197 $67,311 $70,349 $69,266 $69,191 $75,494 $69,140 $82,163 $81,117 $93,348 $82,636 $89,738 $72,299 $63,353 $66,894 $69,781 $89,923 $82,419 $90,184 $73,202 $67,277 $62,600 $81,706 $77,508 $70,394 $77,620 $84,535 $56,280 $74,751 $84,124
2 — 1 2 6 1 2 1 — 8 5 — — 4 4 1 1 1 1 1 1 4 5 3 — 2 — 1 1 1 3 — 7 6 — 3 1 1 4 — — 1 3 6 1 1 2 1 1 1 —
Note: ED ⫽ educational programs; F ⫽ facilities; PTC ⫽ patients treated for cancer; SP ⫽ state populations; T ⫽ radiation therapy; WS ⫽ wage and salary.
Furthermore, there are only 101 radiation therapy programs recognized by the American Registry of Radiologic Technologists in the United States [4], with 11 states not having any programs (Alaska, the District of
Columbia, Hawaii, Idaho, Mississippi, Montana, North Dakota, New Mexico, Rhode Island, South Carolina, and Wyoming). Regardless of this relatively limited number of programs, states that do not have educa-
Culbertson, Carbonneau, Kudlas/State Population and RT Staffing Levels 361 Fig 3. Scatterplot of active registered radiation therapists by persons treated for cancer, 2004.
tional programs still have state population/radiation therapy ratios similar to those states that do have educational programs. For example, comparing the state population/radiation therapy ratio of a mostly rural state (Wyoming) with zero education programs with that of a large urban state (New York) with a high number of education programs (n ⫽ 7) reveals similar ratios (New York, 20,747:1; Wyoming, 22,545:1). In addition, the mean state population/radiation therapy ratio across all states is 20,161:1 (SD, 4,931). This indicates that states that do not have EPs are successful in recruiting radiation therapists from other states to meet their demand. This in turn illustrates that state population is the more parsimonious fit for T [5]. Urban and Academic Centers. An assumption could be
made that urban areas with academic centers and facilities with higher levels of technology would attract a large number of staff members. As with the state population/radiation therapy ratio determined above, we can compute the ratio of therapists per facility and make comparisons among differing states [3]. As seen in Table 2, California has the highest number of facilities (n ⫽ 197) and Alaska the lowest (n ⫽ 3), but the ratios of therapists to facilities are very similar (California, 5.1:1; Alaska, 4.7:1), with the mean number of therapists per facility across all states being 5.8 ⫾ 1.4. This indicates that the number of facilities in a state does not necessarily drive staffing numbers but rather the demand in that state, which can be predicted by state population. Conventionally, variability in salary is often thought of as an indicator of the relative degree to which demand is being met by equilibrium, oversupply, or shortage in supply. Salary data collected from radiation therapists in the American Society of Radiologic Technologists 2010 Wage and Salary Survey [6] (M, $77,076 ⫾ $10,268; n ⫽ 51) does not significantly correlate with radiation therapy (M, 310.4 ⫾ 310.9; n ⫽ 41) by state (r[51] ⫽ 0.240, p ⫽ .089; see Table 2 for wage and salary and radiation therapy data). This illustrates that salary is very complex, with many factors affecting its variance, such as cost-of-living differences within regions (eg, rural, urban, suburban), employee experience, education
level, as well as other variables, and does not contribute as a predictor of radiation therapy with state population in a multiple regression model ( ⫽ ⫺0.002, p ⫽ .085). Limitations
Significant increases in demand over a short time span at the state level could dramatically alter projections of needed supply. Likewise, unexpected shifts in state population would have a similar effect. Controlling for such changes in computing projected demand is recommended, if such patterns are evident. Advancements in technology could also create efficiencies in which the number of staff members needed for patient throughput and workload becomes lower. A possible additional limitation is that any changes in year-to-year facility reimbursement that occur across states could potentially affect staffing patterns. Further research would be required to determine if this is a significant factor that accounts for variability in the model. The association between state population and the number of actively employed radiation therapists does not determine if facilities are appropriately staffed in relation to actual patient throughput and workload. It merely illustrates the relative consistency and equilibrium of staffing levels that occur with state population as a predictor variable. Further research could be conducted to determine if radiation therapists and managers believe their facilities to be appropriately staffed, given actual levels of patient throughput and workload.
Salary.
CONCLUSIONS
This study establishes the association of state population as a significantly strong predictor of radiation therapy staffing levels. Factoring in the number of patients treated in a given state strengthens the model further accounting for an even higher percentage of the variability in radiation therapy staffing levels. Although multicollinearity exists with the number of EPs found in a given state, as a single factor, state population is the more parsimonious fit. Other variables such as salary do not contribute as significant predictors of radiation therapy staffing levels in a multiple regression model.
362 Journal of the American College of Radiology/ Vol. 9 No. 5 May 2012
With state population as a predictor variable, health care professionals can address cycles of shortages and oversupplies of radiation therapy staffing supply by making comparative analyses of changes across these populations. By monitoring these changes, it is possible to estimate future demand for radiation therapy staff members at the state and aggregated national levels.
2. US Census Bureau. National and state population estimates, 2000-2010. Available at: http://www.census.gov/popest/intercensal/state/state2010. html. Accessed November 18, 2011. 3. Ballas LK, Elkin EB, Schrag D, Minsky BD, Bach PB. Radiation therapy facilities in the United States. Int J Radiat Oncol Biol Phys 2006;66:1204-11. 4. American Registry of Radiologic Technologists. ARRT-recognized educational programs. Available at: https://www.arrt.org/Education/EducationalPrograms. Accessed November 18, 2011.
REFERENCES
5. Bentler PM, Mooijaart A. Choice of structural model via parsimony: a rationale based on precision. Psychol Bull 1989;106:315-7.
1. American Society of Radiologic Technologists. Radiation Therapy Staffing Survey. Available at: https://www.asrt.org/content/RTs/Research/research. aspx. Accessed November 18, 2011.
6. American Society of Radiologic Technologists. 2011 Wage and Salary Survey. Available at: https://www.asrt.org/content/RTs/Research/research. aspx. Accessed November 18, 2011.