pre_text: Liability for Warranty Liability for Warranty Our products generally include warranties of 90 days to five years for product defects. We accrue for warranty returns at the time revenue is recognized based on our historical return rate and estimate of the cost to repair or replace the defective products. We engage in extensive product quality programs and processes, including actively monitoring and evaluating the quality of our component suppliers. The increasing complexity of our products will cause warranty incidences, when they arise, to be more costly. Our estimates regarding future warranty obligations may change due to product failure rates, material usage and other rework costs incurred in correcting a product failure. In addition, from time to time, specific warranty accruals may be recorded if unforeseen problems arise. Should our actual experience relative to these factors be worse than our estimates, we will be required to record additional warranty expense. Alternatively, if we provide for more reserves than we require, we will reverse a portion of such provisions in future periods. The liability for warranty obligations totaled $8.4 million and $8.6 million as of December 31, 2019 and 2018, respectively. These liabilities are included in accrued expenses in the accompanying Consolidated Balance Sheets. During 2017, we recorded a reduction in warranty expense related to a settlement with a third-party supplier for a defective component, the impact of which is reflected in the following table. A summary of warranty expense and write-off activity for the years ended December 31, 2019, 2018 and 2017 is as follows: (In thousands)
table: Year Ended December 31, 2019 2018 2017
table: Balance at beginning of period $8,623 $9,724 $8,548
table: Plus: Amounts charged to cost and expenses 4,569 7,392 6,951
table: Less: Deductions (4,798) (8,493) (5,775)
table: Balance at end of period $8,394 $8,623 $9,724
question: Analyse this data from a financial earnings document. What was the change in the balance at the beginning of period between 2018 and 2019?