in System Test was primarily due to lower sales in Storage Test of system level and hard disk drive testers. The decrease in income before taxes in Wireless Test was driven primarily by a decrease in sales of connectivity test products. The decrease in income before taxes in Robotics was driven primarily by lower demand for collaborative robotic arms and autonomous mobile robots. The decrease in loss before income taxes in Corporate and Eliminations was primarily due to legal settlement charges in 2022 related to litigation for the earn-out dispute in connection with the AutoGuide acquisition.
Income Taxes
The effective tax rate for the three months ended April 2, 2023 and April 3, 2022 was 14.0% and 10.2%, respectively. The increase in the effective tax rate from the three months ended April 3, 2022 to the three months ended April 2, 2023 was primarily attributable to a projected shift in the geographic distribution of income, which increases the income subject to taxation in higher tax rate jurisdictions relative to lower tax rate jurisdictions and a decrease in benefit from equity compensation. These increases in expense were partially offset by increases in benefit from the international provisions of the U.S. Tax Cuts and Jobs Act of 2017 and tax credits.
Contractual Obligations
There have been no changes outside of the ordinary course of business to our contractual obligations as disclosed in our Annual Report on Form 10-K for the year ended December 31, 2022.
Liquidity and Capital Resources
Our cash, cash equivalents and marketable securities balances decreased by $146.1 million in the three months ended April 2, 2023 to $859.0 million.
Operating activities during the three months ended April 2, 2023 provided cash of $19.3 million. Changes in operating assets and liabilities used cash of $106.5 million due to a $1.9 million increase in operating assets and a $104.7 million decrease in operating liabilities.
The increase in operating assets was primarily due to a $23.7 million increase in inventories, a $15.4 million increase in prepayments and other assets due to prepayments to our contract manufacturers, partially offset by a $37.2 million decrease in accounts receivable.
The decrease in operating liabilities was due to a $93.1 million decrease in accrued employee compensation, a $32.7 million decrease in deferred revenue and customer advance payments, and $1.2 million of retirement plan contributions, partially offset by a $12.5 million increase in income taxes, a $9.6 million increase in other accrued liabilities, and a $0.3 million increase in accounts payable.
Investing activities during the three months ended April 2, 2023 used cash of $94.9 million due to $69.3 million used for purchases of marketable securities, and $41.4 million used for purchases of property, plant and equipment, partially offset by $7.9 million and $7.4 million in proceeds from sales and maturities of marketable securities, respectively, and $0.5 million in proceeds from the cancellation of Teradyne owned life insurance policies related to the cash surrender value.
Financing activities during the three months ended April 2, 2023 used cash of $129.5 million due to $93.3 million used for the repurchase of 0.9 million shares of common stock at an average price of $104.88 per share, $19.9 million used for payment related to net settlements of employee stock compensation awards, $17.2 million used for dividend payments, and $15.2 million used for payments of convertible debt principal, partially offset by $16.0 million from the issuance of common stock under employee stock purchase and stock option plans.
Operating activities during the three months ended April 3, 2022 provided cash of $7.5 million. Changes in operating assets and liabilities used cash of $210.2 million. This was due to an $83.6 million increase in operating assets and a $126.6 million decrease in operating liabilities.
The increase in operating assets was due to a $74.3 million increase in prepayments and other assets due to prepayments to our contract manufacturers, a $9.5 million increase in inventories, partially offset by a $0.2 million decrease in accounts receivable.
The decrease in operating liabilities was due to a $114.0 million decrease in accrued employee compensation, a $13.8 million decrease in other accrued liabilities, a $7.6 million decrease in income taxes, and $1.3 million of retirement plan contributions, partially offset by a $6.7 million increase in deferred revenue and customer advance payments, and a $3.4 million increase in accounts payable.
Investing activities during the three months ended April 3, 2022 used cash of $82.7 million due to $166.0 million used for purchases of marketable securities and $44.0 million used for purchases of property, plant and equipment, partially offset by $96.7 million and $30.6 million in proceeds from maturities and sales of marketable securities, respectively.
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