网站首屏设计AB测试

研究方法

作者

yangjh

发布日期

November 28, 2022

import pandas as pd
import numpy as np
import plotly.express as px
import mytools

#| echo: false
import plotly.io as pio

# 设置默认渲染器为 SVG
pio.renderers.default = "svg"

df1 = pd.read_excel(R"data\ABtest_actions_full.xlsx")

解释性研究是关于现象或事物之间因果关系的研究。解释性研究是在描述性研究的基础上，进一步探寻“为什么”。解释性研究要在描述性研究的基础上对变量之间的关系进行分析，以确定它们之间是否存在相关，并进而判断它们之间是否存在因果关系。

在定量研究方法中，解释性研究通常是首先提出研究假设，然后从理论假设出发，设计出调查方案（收集资料的方案）并采用各种调查方法去收集经验材料，最后通过对资料的分析来验证假设，达到对社会现象进行理论解释的目的。

明确数据分析目标

本案例属于解释性研究，也可以认为是评价性研究。

某在线教育机构，需要评价网站首页改版是否有效，进行了在线AB测试，在一段时间内，将访问用户随机分成2部分，分别访问原首页和改版后首页，搜集用户的浏览、点击和报名行为。

研究假设：改版后报名比例高于改版前的报名比例。原假设：改版后报名比例小于等于改版前的报名比例。

数据获取

本研究采用在线AB实验法，在XXX与XX期间，对访问网站首页的用户进行随机分组分流，50%的用户访问原首页，50%的用户访问新首页，共获得样本数据XXX个。

数据清理

查看所有空白值

temp = df1[df1.isnull().T.any()]
temp

	timestamp	id	group	action	duration
12	2016-09-24 22:43:35.120	701620	control	view	NaN
227	2016-09-30 11:57:44.059	802405	control	view	NaN
236	2016-09-30 17:17:07.709	524941	control	view	NaN
261	2016-10-01 08:40:31.380	381758	control	view	NaN
367	2016-10-03 20:08:57.011	757165	control	enroll	NaN
605	2016-10-10 11:26:20.715	678491	control	view	NaN
731	2016-10-14 04:19:46.021	878418	control	view	NaN
1145	2016-10-27 04:48:21.083	767153	control	view	NaN
1212	2016-10-29 09:37:41.649	196115	control	enroll	NaN
1238	2016-10-29 23:41:44.643	542999	control	view	NaN
1311	2016-11-01 05:42:50.439	599303	control	view	NaN
1322	2016-11-01 10:07:53.009	281907	control	view	NaN
1663	2016-11-11 13:56:17.708	742859	control	view	NaN
1768	2016-11-14 12:04:15.515	860051	control	view	NaN
1966	2016-11-20 09:06:10.553	864971	control	view	NaN
2457	2016-12-04 22:55:30.055	443391	control	enroll	NaN
2576	2016-12-08 11:34:10.808	928935	control	view	NaN
2700	2016-12-11 18:23:52.131	417569	control	view	NaN
2766	2016-12-13 10:17:36.711	496865	control	view	NaN
2834	2016-12-14 17:24:26.749	429709	control	enroll	NaN
3660	2017-01-07 08:14:30.071	631083	control	enroll	NaN
3754	2017-01-10 01:45:10.342	403964	control	view	NaN
3758	2017-01-10 03:04:52.819	883792	control	view	NaN
3798	2017-01-11 05:16:49.001	910942	control	view	NaN
3965	2017-01-15 20:17:33.700	508697	control	view	NaN

## 删除空值
df2 = df1.dropna()

## 查看重复值
df2[df2.duplicated(subset=['id','group','action'],keep='first')][['id','group','action']]

	id	group	action
5	261869	experiment	view
6	226546	experiment	view
7	286353	experiment	view
8	842279	experiment	view
142	711838	experiment	view
971	724590	experiment	view
1013	314669	experiment	view
1351	381744	experiment	view
1765	831767	experiment	view
1902	655009	experiment	view
2293	645047	experiment	view
2704	510055	experiment	view
2919	661526	experiment	view
2952	885859	experiment	view
3559	661528	experiment	view
3653	191559	experiment	view

# 删除重复值
df3 = df2.drop_duplicates(subset=['id'],keep='last')

查看变量类型

df3.dtypes.to_frame()

	0
timestamp	datetime64[ns]
id	int64
group	object
action	object
duration	float64

# 指定变量的类型
df4 = df3.astype({
    'group': 'category',
    'action': 'category',
})
df4.dtypes.to_frame()

	0
timestamp	datetime64[ns]
id	int64
group	category
action	category
duration	float64

## 异常值查找
df4['duration'].describe()

count    4028.000000
mean      123.402057
std        72.587800
min         0.013856
25%        67.080495
50%       118.487843
75%       172.580542
max       421.567520
Name: duration, dtype: float64

fig = px.box(df4, y="duration")
fig.show()

Unable to display output for mime type(s): application/vnd.plotly.v1+json

fig = px.histogram(df4, x="duration")
fig.show()

Unable to display output for mime type(s): application/vnd.plotly.v1+json

# 数据清理完毕

df = df4.copy()

数据分析

描述统计

先描述样本背景，对样本质量进行评价。再描述样本特征信息、样本基本现状，最后描述样本基本态度及其他维度。

描述统计分析也应该有理论依据或概念合理的分类。

推论统计

可进行一些相关性、差异性分析以及回归分析。合理分析变量之间的相关性。

## 样本规模
N = df.shape[0]
print(N)

mytools.gen_percent_table(df,'group')

	group	个数	百分比
0	experiment	2079	51.61
1	control	1949	48.39
2	总和	4028	100.00

# 构建绘图用数据表
sun_df = df.groupby(["group",'action']).size().reset_index(name='频数')
sun_df

	group	action	频数
0	control	enroll	370
1	control	view	1579
2	experiment	enroll	438
3	experiment	view	1641

temp = sun_df.set_index(['group','action'])
temp['%'] = 100 * (temp / temp.groupby('group').sum())
temp.round(2)

		频数	%
group	action
control	enroll	370	18.98
control	view	1579	81.02
experiment	enroll	438	21.07
experiment	view	1641	78.93

sun_df = temp.reset_index()
sun_df

	group	action	频数	%
0	control	enroll	370	18.984094
1	control	view	1579	81.015906
2	experiment	enroll	438	21.067821
3	experiment	view	1641	78.932179

fig = px.bar(
    sun_df,  # 带绘图数据 
    x="group",  # x轴
    y="%",  # y轴
    color="group",
    facet_col="action",  # 列
)
fig.show()

Unable to display output for mime type(s): application/vnd.plotly.v1+json

fig = px.pie(df,names="action")
fig.show()

Unable to display output for mime type(s): application/vnd.plotly.v1+json

fig = px.sunburst(sun_df,
                  path=['group','action'], 
                  values='%'
                 )
fig.show()

Unable to display output for mime type(s): application/vnd.plotly.v1+json

### 双变量统计分析
result = pd.crosstab(
        df['action'],
        df['group'],
        normalize='columns',
        margins=True,
        margins_name='合计',
    )*100
result.round(2)

group	control	experiment	合计
action
enroll	18.98	21.07	20.06
view	81.02	78.93	79.94

可通过Z检验，对两个比例值是否存在统计显著性差异进行检验。

n1 = df.query('group =="control"').shape[0]
n2 = df.query('group =="experiment"').shape[0]
p1 = df.query('group =="control" and action =="enroll"').shape[0] / n1
p2 = df.query('group =="experiment" and action =="enroll"').shape[0] / n2
z, p_value = mytools.two_prop_equal_test(n1, n2, p1, p2)
print(z, p_value)

-1.6503840862221497 0.049432201929688536

通过对AB测试的结果进行分析，发现实验组的报名比例较控制组有所增高，p=0.049，具有统计显著性，拒绝原假设，接受研究假设，即：改版后的首页较原版有利于提高学员报名率。

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