*** Original data set
Array
(
    [0] => 2
    [1] => 2.3
    [2] => 4.5
    [3] => 2
    [4] => 2
    [5] => 3.2
    [6] => 5.3
    [7] => 3
    [8] => 4
    [9] => 5
    [10] => 1
    [11] => 6
)
Basic statistics
Array
(
    [min] => 1
    [max] => 6
    [sum] => 40.3
    [sum2] => 162.87
    [count] => 12
    [mean] => 3.3583333333333
    [stdev] => 1.58197709059
    [variance] => 2.5026515151515
)

*** A data set with nulls
Array
(
    [0] => 1.165
    [1] => 
    [2] => foo
    [3] => 0.6268
    [4] => 0.6268
    [5] => 0.0751
    [6] => 0.3516
    [7] => -0.6965
)
Let's generate an error
PEAR_Error Object
(
    [error_message_prefix] => 
    [mode] => 1
    [level] => 1024
    [code] => 
    [message] => data rejected, contains NULL values
    [userinfo] => 
    [backtrace] => Array
        (
            [0] => Array
                (
                    [file] => /opt/lampp/lib/php/PEAR.php
                    [line] => 577
                    [function] => __construct
                    [class] => PEAR_Error
                    [type] => ->
                    [args] => Array
                        (
                            [0] => data rejected, contains NULL values
                            [1] => 
                            [2] => 1
                            [3] => 1024
                            [4] => 
                        )

                )

            [1] => Array
                (
                    [file] => /opt/lampp/lib/php/PEAR.php
                    [line] => 236
                    [function] => _raiseError
                    [class] => PEAR
                    [type] => ::
                    [args] => Array
                        (
                            [0] => 
                            [1] => data rejected, contains NULL values
                        )

                )

            [2] => Array
                (
                    [file] => /opt/lampp/lib/php/Math/Stats.php
                    [line] => 868
                    [function] => __callStatic
                    [class] => PEAR
                    [type] => ::
                    [args] => Array
                        (
                            [0] => raiseError
                            [1] => Array
                                (
                                    [0] => data rejected, contains NULL values
                                )

                        )

                )

            [3] => Array
                (
                    [file] => /opt/lampp/lib/php/Math/Stats.php
                    [line] => 183
                    [function] => _validate
                    [class] => Math_Stats
                    [object] => Math_Stats Object
                        (
                            [_data] => Array
                                (
                                    [0] => 1.165
                                    [1] => 
                                    [2] => foo
                                    [3] => 0.6268
                                    [4] => 0.6268
                                    [5] => 0.0751
                                    [6] => 0.3516
                                    [7] => -0.6965
                                )

                            [_dataOption] => 0
                            [_nullOption] => 
                        )

                    [type] => ->
                    [args] => Array
                        (
                        )

                )

            [4] => Array
                (
                    [file] => /opt/lampp/lib/php/Math/examples/ex_stats_simple.php
                    [line] => 45
                    [function] => setData
                    [class] => Math_Stats
                    [object] => Math_Stats Object
                        (
                            [_data] => Array
                                (
                                    [0] => 1.165
                                    [1] => 
                                    [2] => foo
                                    [3] => 0.6268
                                    [4] => 0.6268
                                    [5] => 0.0751
                                    [6] => 0.3516
                                    [7] => -0.6965
                                )

                            [_dataOption] => 0
                            [_nullOption] => 
                        )

                    [type] => ->
                    [args] => Array
                        (
                            [0] => Array
                                (
                                    [0] => 1.165
                                    [1] => 
                                    [2] => foo
                                    [3] => 0.6268
                                    [4] => 0.6268
                                    [5] => 0.0751
                                    [6] => 0.3516
                                    [7] => -0.6965
                                )

                        )

                )

        )

    [callback] => 
)
Ignoring nulls and trying again
---> data after ignoring (removing) nulls
Array
(
    [0] => 1.165
    [3] => 0.6268
    [4] => 0.6268
    [5] => 0.0751
    [6] => 0.3516
    [7] => -0.6965
)
---> stats
Array
(
    [min] => -0.6965
    [max] => 1.165
    [sum] => 2.1488
    [sum2] => 2.7573563
    [count] => 6
    [mean] => 0.35813333333333
    [stdev] => 0.63052349572928
    [variance] => 0.39755987866667
)
Assuming nulls are zeros and doing a full stats calculation
---> data after setting nulls to zero
Array
(
    [0] => 1.165
    [1] => 0
    [2] => 0
    [3] => 0.6268
    [4] => 0.6268
    [5] => 0.0751
    [6] => 0.3516
    [7] => -0.6965
)
---> stats
Array
(
    [min] => -0.6965
    [max] => 1.165
    [sum] => 2.1488
    [sum2] => 2.7573563
    [count] => 8
    [mean] => 0.2686
    [median] => 0.21335
    [mode] => Array
        (
            [0] => 0
            [1] => 0.6268
        )

    [midrange] => 0.23425
    [stdev] => 0.55808199858341
    [absdev] => 0.42395
    [variance] => 0.31145551714286
    [std_error_of_mean] => 0.19731178282824
    [skewness] => -0.09502438055225
    [kurtosis] => -0.99237528491194
    [coeff_of_variation] => 2.0777438517625
    [sample_central_moments] => Array
        (
            [1] => 0
            [2] => 0.2725235775
            [3] => -0.01651692093225
            [4] => 0.19474871029078
            [5] => -0.031219705851295
        )

    [sample_raw_moments] => Array
        (
            [1] => 0.2686
            [2] => 0.3446695375
            [3] => 0.22246098267325
            [4] => 0.30017682071373
            [5] => 0.27262031669782
        )

    [frequency] => Array
        (
            [1.165] => 1
            [0] => 2
            [0.6268] => 2
            [0.0751] => 1
            [0.3516] => 1
            [-0.6965] => 1
        )

)