Our rationale for using these non-GAAP financial measures, as well as their impact on the presentation of Qorvo's operations, are outlined below:
Non-GAAP gross profit and gross margin. Non-GAAP gross profit and gross margin exclude stock-based compensation expense, amortization of intangible assets, accelerated depreciation, restructuring related charges and certain non-cash expenses. We believe that exclusion of these costs in presenting non-GAAP gross profit and gross margin gives management and investors a more effective means of evaluating Qorvo's historical performance and projected costs and the potential for realizing cost efficiencies. We believe that the majority of Qorvo's purchased intangibles are not relevant to analyzing current operations because they generally represent costs incurred by the acquired company to build value prior to acquisition, and thus are effectively part of transaction costs rather than ongoing costs of operating Qorvo's business. In this regard, we note that (i) once the intangibles are fully amortized, the intangibles will not be replaced with cash costs and therefore, the exclusion of these costs provides management and investors with better visibility into the actual costs required to generate revenues over time, and (ii) although we set the amortization expense based on useful life of the various assets at the time of the transaction, we cannot influence the timing and amount of the future amortization expense recognition once the lives are established. Similarly, we believe that presentation of non-GAAP gross profit and gross margin and other non-GAAP financial measures that exclude the impact of stock-based compensation expense assists management and investors in evaluating the period-over-period performance of Qorvo's ongoing operations because (i) the expenses are non-cash in nature, and (ii) although the size of the grants is within our control, the amount of expense varies depending on factors such as short-term fluctuations in stock price volatility and prevailing interest rates, which can be unrelated to the operational performance of Qorvo during the period in which the expense is incurred and generally are outside the control of management. Moreover, we believe that the exclusion of stock-based compensation expense in presenting non-GAAP gross profit and gross margin and other non-GAAP financial measures is useful to investors to understand the impact of the expensing of stock-based compensation to Qorvo's gross profit and gross margins and other financial measures in comparison to prior periods. We also believe that the adjustments to profit and margin related to accelerated depreciation, restructuring related charges and certain non-cash expenses do not constitute part of Qorvo's ongoing operations and therefore the exclusion of these items provides management and investors with better visibility into the actual revenue and actual costs required to generate revenues over time and gives management and investors a more effective means of evaluating our historical and projected performance. We believe disclosure of non-GAAP gross profit and gross margin has economic substance because the excluded expenses do not represent continuing cash expenditures and, as described above, we have little control over the timing and amount of the expenses in question.
Non-GAAP operating income and operating margin. Non-GAAP operating income and operating margin exclude stock-based compensation expense, amortization of intangible assets, restructuring related charges, acquisition and integration related costs, asset impairment and accelerated depreciation, (gain) loss on assets, start-up costs and certain non-cash expenses. We believe that presentation of a measure of operating income and operating margin that excludes amortization of intangible assets and stock-based compensation expense is useful to both management and investors for the same reasons as described above with respect to our use of non-GAAP gross profit and gross margin. We believe that restructuring related charges, acquisition and integration related costs, asset impairment and accelerated depreciation, (gain) loss on assets, start-up costs and certain non-cash expenses do not constitute part of Qorvo's ongoing operations and therefore, the exclusion of these costs provides management and investors with better visibility into the actual costs required to generate revenues over time and gives management and investors a more effective means of evaluating our historical and projected performance. We believe disclosure of non-GAAP operating income and operating margin has economic substance because the excluded expenses are either unrelated to ongoing operations or do not represent current cash expenditures.
Non-GAAP net income and non-GAAP net income per diluted share. Non-GAAP net income and non-GAAP net income per diluted share exclude the effects of stock-based compensation expense, amortization of intangible assets, restructuring related charges, acquisition and integration related costs, asset impairment and accelerated depreciation, (gain) loss on assets, start-up costs, certain non-cash expenses, loss (gain) on investments, other (income) expense and also reflect an adjustment of income taxes. The income tax adjustment primarily represents the use of research and development tax credit carryforwards, deferred tax expense (benefit) items not affecting taxes payable, adjustments related to the deemed and actual repatriation of historical foreign earnings, non-cash expense (benefit) related to uncertain tax positions and other items unrelated to the current fiscal year or that are not indicative of our ongoing business operations. We believe that presentation of measures of net income and net income per diluted share that exclude these items is useful to both management and investors for the reasons described above with respect to non-GAAP gross profit and gross margin and non-GAAP operating income and operating margin. We believe disclosure of non-GAAP net income and non-GAAP net income per diluted share has economic substance because the excluded expenses are either unrelated to ongoing operations or do not represent current cash expenditures.
Non-GAAP research and development and selling, general and administrative expenses. Non-GAAP research and development and selling, general and administrative expenses exclude stock-based compensation expense, amortization of intangible assets and certain non-cash expenses (primarily acquisition and integration related costs). We believe that presentation of measures of these operating expenses that exclude amortization of intangible assets and stock-based compensation expense is useful to both management and investors for the same reasons as described above with respect to our use of non-GAAP gross profit and gross margin. We believe that acquisition and integration related costs and certain non-cash expenses do not constitute part of Qorvo's ongoing operations and therefore, the exclusion of these costs provides management and investors with better visibility into the actual costs required to generate revenues over time and gives management and investors a more effective means of evaluating our historical and projected performance. We believe disclosure of these non-GAAP operating expenses has economic substance because the excluded expenses are either unrelated to ongoing operations or do not represent current cash expenditures.
Free cash flow. Qorvo defines free cash flow as net cash provided by operating activities during the period minus property and equipment expenditures made during the period. We use free cash flow as a supplemental financial measure in our evaluation of liquidity and financial strength. Management believes that this measure is useful as an indicator of our ability to service our debt, meet other payment obligations and make strategic investments. Free cash flow should be considered in addition to, rather than as a substitute for, net income as a measure of our performance and net cash provided by operating activities as a measure of our liquidity. Additionally, our definition of free cash flow is limited, in that it does not represent residual cash flows available for discretionary expenditures due to the fact that the measure does not deduct the payments required for debt service and other contractual obligations. Therefore, we believe it is important to view free cash flow as a measure that provides supplemental information to our entire statement of cash flows.
EBITDA. Qorvo defines EBITDA as earnings before interest expense and interest income, income tax expense (benefit), depreciation and intangible amortization. Management believes that this measure is useful to evaluate our ongoing operations and as a general indicator of our operating cash flow (in conjunction with a cash flow statement which also includes among other items, changes in working capital and the effect of non-cash charges).
Non-GAAP ROIC. Return on invested capital (ROIC) is a non-GAAP financial measure that management believes provides useful supplemental information for management and the investor by measuring the effectiveness of our operations' use of invested capital to generate profits. We use ROIC to track how much value we are creating for our shareholders. Non-GAAP ROIC is calculated by dividing annualized non-GAAP operating income, net of an adjustment for income taxes (as described above), by average invested capital. Average invested capital is calculated by subtracting the average of the beginning balance and the ending balance of current liabilities (excluding the current portion of long-term debt and other short-term financings) from the average of the beginning balance and the ending balance of net accounts receivable, inventories, other current assets, net property and equipment and a cash amount equal to seven days of quarterly revenue.
