Consolidated Statements of Cash Flows For the Years Ended December 31, 1998, 1999, and 2000 (in thousands) f-16 | 17 Forrester Research | Annual Report 2000 1998 1999 2000 Cash flows from operating activities: Net income $ 7,547 $ 10,981 $ 21,614 Adjustments to reconcile net income to net cash  provided by (used in) operating activities — Depreciation and amortization 2,763 4,003 7,944 Write-down of non-marketable investment — — 950 Loss on disposals of property and equipment — 105 376 Deferred income taxes 288 464 13,593 Increase in provision for doubtful accounts 375 904 1,246 Accretion of discount on marketable securities (55) (50) (178) Changes in assets and liabilities — Accounts receivable (10,340) (15,940) (13,817) Deferred commissions (756) (2,726) (3,023) Prepaid income taxes 186 (853) (2,446) Prepaid expenses and other current assets (1,415) (1,610) (1,924) Accounts payable 171 1,103 1,931 Customer deposits (15) 452 459 Accrued expenses 1,400 3,875 6,342 Accrued income taxes 2,341 4,716 1,156 Deferred revenue 11,820 26,521 35,745 Net cash provided by operating activities 14,310 31,945 69,968 Cash flows from investing activities: Net cash acquired (paid) in acquisitions (Note 2) — 355 (14,851) Purchases of property and equipment (6,087) (8,892) (18,044) Proceeds related to disposals of property  and equipment — 1,056 — Purchases of non-marketable investment — (1,000) (6,681) Decrease in other assets — (835) (45) Purchases of marketable securities (313,236) (466,628) (354,613) Proceeds from sales and maturities of  marketable securities 304,482 436,843 282,021 Net cash used in investing activities (14,841) (39,101) (112,213) Cash flows from financing activities: Net proceeds from public offering of  common stock  — — 22,659 Proceeds from issuance of common stock  under stock option plans and employee  stock purchase plan 3,193 10,192 21,825 Net cash provided by financing activities 3,193 10,192 44,484 Effect of exchange rate changes on cash  and cash equivalents 10 (5) 164 Net increase in cash and cash equivalents 2,672 3,031 2,403 Cash and cash equivalents, beginning of year 7,742 10,414 13,445 Cash and cash equivalents, end of year $ 10,414 $ 13,445 $ 15,848